Appropriate Sanitation Alternatives /f ;L
A Technical and Economic Appraisal
John M. Kalbermatten * DeAnne S. Julius * Charles G. Gunnerson
H Kb
World Bank Studies in Water Supply and Sanitation 1
Appropriate Sanitation Alternatives
A Technical and Economic Appraisal
WORLID BANK STUDIES IN
WATER SUPPLY AND SANITATION
1
A i I~ ~~~~~~~~~~~~~~~~~ I
Appropriate Sanitation Alternatives
A Technical and Economic Appraisal
John M. Kalbermatten, DeAnne S. Julius,
and Charles G. Gunnerson
Published for The World Bank
The Johns Hopkins University Press
Baltimore and London
Copyright �C 1982 by the International Bank for Reconstruction
and Development / THE WORLD BANK
1818 H Street, N.W., Washington, D.C. 20433, U.S.A.
All rights reserved
Manufactured in the United States of America
The Johns Hopkins University Press
Baltimore, Maryland 21218, U.S.A.
The views and interpretations in this book are the authors' and should
not be attributed to the World Bank, to its affiliated organizations, or
to any individual acting in their behalf.
EDITOR James McEuen
PRODUCTION Virginia deHaven Hitchcock
FIGURES Pensri Kimpitak
BOOK DESIGN Brian J. Svikhart
COVER DESIGN George Parakamannil
Library of Congress Cataloging in Publication Data
Kalbermatten, John M.
Appropriate sanitation alternatives.
(World Bank studies in water supply and
sanitation; 1)
Bibliography: p.
Includes index.
1. Underdeveloped areas-Sanitary engineering.
l. Julius, DeAnne S., 1949- . II. Gunnerson,
Charles G. III. Title. IV. Series.
TD353.K26 628.1'09172'4 80-8963
ISBN 0-8018-2578-4 (v. 1: pbk.)
Contents
Foreword vii Part Two. Program Planning and Development
Preface ix 6. Implementation of Appropriate Sa,iitation
Acronyms and Abbreviations xii Technology 85
Obstacles 85
1. An Overview 3 Incentives 86
Water Supply and Sanitation in
Developing Countries 3 7. Institutional Requirements 89
An Operational Definition of Appropriate Essential Components 89
Technology 5 Policy Implementation 90
Organizational Issues 90
Part One. Analysis of Field Study Results Division of Responsibihties 91
2. Technical and Environmental Assessment 11 8. Community Participation and Organization
Household Sanitation Systems 11 93
Community Sanitation Systems 16 Objectives 93
Factors Affecting Choice of Scope 93
Technology 18 Implementation 94
Comparison of Technology 42 Linkage of the Institution and
Treatment Alternatives 42 Community 95
Sullage Disposal 43
Resource Recovery 44 9. Project Development 97
Example of Management Schemes for Types of Sanitation Projects 97
Sewerage and Night Soil 46 Technology Selection 99
Future Resource Needs 47 Sanitation Sequences 101
Conclusion 47 Sample Staged Solutions 105
3. The Economic Comparison 50 10. A Concluding Note 108
Economic Costing in Theory 51
Special Problems of Sanitation Bibliography 110
Projects 52 Index 113
Field Results 54
Controlled Comparisons 59
Benefits from Reuse 61 Figures
Financial Implications 63 1-1. Recommended Structure of Feasibility
Conclusion 65 Studies for Sanitation Program Planning 6
4. Public Health Aspects 67 2-1. Generic Classification of Sanitation
Water and Health 67 Systems 14
Excreted Infections 68 2-2. Special Plan of Two Low-income Urban
Environmental Classification of Excreted Residential Neighborhoods 38
Infections 70 2-3. Typical Floor Plan of Low-income Rental
Health Effects of Treatment and Units 40
Reclamation 73 2-4. Schematic of Relations between Levels of
Conclusion 75 Water Service and Options for
5. Sociocultural Factors 77 Sanitation 41
Survey Results 78 2-5. Schematic of Beltsville Agricultural
Behavioral Science and Sanitation Research Center (BARC) System for High-
Project Design 79 rate Thermophilic Composting 46
Conclusion 82 3-1. Benefit-Cost Divergence over Time 52
v
vi
4-1. Influence of Time and Temperature on 18. Known Geographical Distribution of Taenia
Selected Pathogens in Night Soil and solium 36
Sludge 74 19. Known Geographical Distribution of Culex
5-1. The Sociocultural Dimension of Sanitation pipiens 37
Project Design: Contributions of Social 20. Sewerage and Night Soil Collection Areas in
Science 80 the City of Kyoto, Japan 48
9-1. First-stage Algorithm for Selection of
Sanitation Technology 100 Tables
9-2. Second-stage Algorithm for Selection of 2-1. Water Service Levels for Selected Study
Sanitation Technology 102 ..
9-3. Third-stage Algorithm for Selection of Communities 12
^ . . , ^,10 2-2. Sanitation Systems for Selected Study
Sanitation Technotogy 03 Communities 13
9-4. Potential Sanitation Sequences 104 2-3. Descriptive Comparison of Sanitation
9-5. Sample Sanitation Sequences 105 Technologies 44
Maps 3-1. Summary of Total Annual Cost per
Household (TACH) for Sanitation
1. Average January Temperature 19 Technologies 55
2. Average July Temperature 20 3-2. Selected Input Cost and Conversion Factors
3. Generalized Annual Global for Sanitation Technologies 56
Precipitation 21 3-3. Average Annual Investment and Recurrent
4. Temperature and Precipitation, Central and Cost per Household for Sanitation
S-outh America 22Tehogis5
5. Temperature and Precipitation, Asia 23 Technologies 57
3-4. Percentage Investment and Recurrent Cost
6. Temperature and Precipitation, Africa 24 of Community Sanitation Svstems 57
7. Aridity Index for Asia 25 3-5. Average Annual On-site, Collection, and
8. Aridity Index for North and South Treatment Costs per Household 58
America 26 3-6 Annual Sewerage Costs per Household 59
9. Aridity Index for Africa and Australia 27 3-7. Annual Vacuum Cartage Costs per
10. Potential Productivity by Annual Carbon Household 59
Fixation 28 3-8. Comparative TACH5 of Sewerage and
11. Generalized Distribution of Soil Types and Vacuum-truck Cartage in Malacca,
Processes 29 Malaysia 60
12. Trend of the Global Spread of Cholera, 3-9. Comparative TACHS of On-site Systems and
1 61-75 30 Sewerage in Gaborone, Botswana 61
13. Known Geographical Distribution of 3-10. Net Cost of Household Biogas Unit, Island
Schistosoma haematobium and S. of Taiwan 62
japonicum 31 3-11. Financial Requirements for Investment and
14. Known Geographical Distribution of Recurrent Cost per Household 64
Schistosoma mansoni 32
15. Known Geographical Distribution of 4-1. Excreted Infections 71
Ancylostoma duodenale 33 4-2. Environmental Classification of Excreted
16. Known Geographical Distribution of Necator Infections 72
americanus 34 4-3. Potential Health Improvements 76
17. Known Geographical Distribution of Taenia 7-1. Institutional Responsibilities in
saginata 35 Sanitation 92
Foreword
DESPITE THE IMPRESSIVE LEVEL of economic growth fits were developed. Emphasis was also given to the
the developing countries as a whole have achieved over effects of water service levels upon waste disposal
the past quarter century, most of the people in these options and, where applicable, to opportunities for
countries do not have a safe water supply or even recovering some of the costs by physically recycling
rudimentary sanitation. Immediate investment costs the water and fertilizer components of the wastes.
for providing these services at the standards which This is the first of a series of volumes that document
prevail in developed countries are estimated at over the Bank's research findings. Based on case studies in
US$800,000 million. Corresponding operating costs thirty-nine communities around the world, it presents
are projected at another US$10,000 million per year. to planning officials and senior policy advisers a tech-
These amounts vastly exceed the resources available nical and economic assessment of the many sanitation
for the sector. To help address this problem, a two- options that are available and appropriate to condi-
year research project to develop more appropriate tions in developing countries. Other volumes in the
(that is, lower-cost) technologies for water supply and series include a planning and design manual for proj-
waste disposal was undertaken by the World Bank in ect engineers, analysts, and technicians and a compila-
1976-78. Meanwhile, the member countries of the tion and synthesis of health and disease factors impor-
United Nations have declared the 1980s to be the tant in sanitation system planning and implementa-
International Drinking Water Supply and Sanitation tion. Their publication is particularly timely at the
Decade, with the objective of satisfying for all popula- beginning of this decade. If the twin objectives of
tions of the globe two of the most basic human economic growth and the eradication of absolute pov-
needs-clean water and the sanitary disposal of hu- erty are to be met, the nations of the world must
man wastes. ensure that everyone has access to safe water and
The Bank's research revealed the technological, eco- adequate sanitation. It is to universal access to the
nomic, environmental, and institutional interdepen- latter that this volume is dedicated.
dence of water supply, sanitation, and health. Waste
disposal technologies costing as little as one-tenth the WARREN C. BAUM
amount of conventional sewerage were identified. Vice President, Central Projects Staff
Means to ensure high health and environmental bene- The World Bank
vii
I I
Preface
OVER THE PAST DECADE, the focus of development tions entitled "World Bank Studies in Water Supply
planners on economic growth has broadened to include and Sanitation," of which this appraisal is number 1.
a parallel concern with the distribution of the benefits Other publications in this collection include:
made possible by that growth. In his president's address John M. Kalbermatten and others, Appropriaie
to the Board of Governors of the World Bank at its 1980 Sanitation Alternatives: A Planning and Design
annual meeting, Robert S. McNamara reiterated that, Manual, World Bank Studies in Water Supply and
to achieve the twin objectives of economic growth and Sanitation, no. 2
the eradication of absolute poverty, countries must do
two basic things: assist the poor to increase their Richard G. Feachem and others, Sanitation and
productivity and ensure their access to essential public Disease: Health Aspects of Exereta and Wastewater
services. Management, World Bank Studies in Water Supply
Among these essential public services are water and Sanitation, no. 3
supply and waste disposal. Few other services contrib-
ute as much to an improvement in health and living Further publications in the collection will be issued as
standards as does the provision of an adequate supply of ongoing research is completed. In addition, the Trans-
safe water and the means for sanitary disposal of waste. portation, Water, and Telecommunications Depart-
It has become apparent, however, that development ment (TWT) of the World Bank maintains a series of
projects must be specifically designed to reach the reports- under the main title Appropriate Technology
urban and rural poor if the poor are to be provided with for Water Supply and Sanitation-available from the
services that they can afford and that meet their needs. Bank's Publications Unit. Subtitles of volumes in this
In particular, sewerage-the conventional method of series are as follows:
human waste disposal in the developed countries-re- vol. 1: Technical and Economic Options, by John M.
quires massive investments of both foreign and local Kalbermatten, DeAnne S. Julius, and Charles
capital that generally are not available in the develop- G. Gunnerson
ing nations. Where sewerage systems have been built,
they often have required charges to the consumers that . 1aS
were beyond consumers' ability to pay. In acknowledg- tions
ment of the limitations of traditional solutions, the vol. 2: A Planner's Guide, by John M. Kalbermat-
World Bank in 1976 launched a two-year research ten, DeAnne S. Julius, Charles G. Gunnerson,
project entitled "Appropriate Technology for Water and D. Duncan Mara
Supply and Waste Disposal in Developing Countries." vol. 3: Health Aspects of Excreta and Sullage
The objective of the project was to identify and evaluate Management-A State-of-the-Art Review,
alternative sanitation technologies for their potential to by Richard G. Feachem, David J. Bradley,
meet the needs and match the resources of project Hemda Garelick, and D. Duncan Mara
beneficiaries.
To accomplish this, the health, social, institutional, vol. 4: Low-Cost Technology Options for Sanita-
as well as the technical and economic aspects of the tion-A State-of-the-Art Review and Anno-
various technologies had to be considered. The overall tated Bibliography, by Witold Rybczynski,
project has consequently generated a variety of subsid- Chongrak Polprasert, and Michael McGarry
iary research by specialists in different disciplines, and [available, as a joint World Bank/Interna-
its findings are being issued in a collection of publica- tional Development Research Centre publica-
Ix
x
tion, from the IDRC, Ottawa, Ontario, Can- and many variations of each type were observed.
adal Improved designs were prepared for several of these,
vol. 5: Sociocultural Aspects of Water Supply and and for only one technology (bucket latrines) was it
Excreta Disposal, by Mary Elmendorf and concluded that introduction of a system to new sites
Patricia Buckles should be avoided. Two of the other technologies,
vol. 6: Country Studies in Sanitation Alternatives, aquaprivies and communal facilities, were found to
by Richard A. Kuhlthau (ed.) have limited applicability because of social factors. All
vol. 7: Alternative Sanitation Technologies for Ur- of the remaining technologies (improved pit latrines,
ban Areas in Africa, By Richard G. Feachem, pour-flush (PF) toilets, composting toilets, modified
D. Duncan Mara, and Kenneth 0. Iwugo septic tanks, vault and cartage, small-bore sewerage,
vol. 8: Seven Case Studies of Rural and Urban and conventional sewerage) can be recommended (sub-
Fringe Areas in Latin America, by Mary ject to the physical conditions of the site and the social
Elmendorf (ed.) preferences and economic resources of the beneficia-
vol. 9: Low-Cost Design of Water Distribution Sys- ries) for adoption. Except in unusual circumstances,
tems, by Donald T. Lauria, Peter J. Kolsky, both scattered, rural and densely populated, urban
and Richard N. Middleton communities should find themselves with two or more
vol. I ONight-soil Composting, by Hillel I. Shuval, technically feasible options, each with a range of design
Charles G. Gunnerson, and DeAnne S. Julius alternatives.
vol. 11 A Sanitation Field Manual, by John M. Another important technical contribution of this
Kalbermatten, DeAnne S. Julius, and Charles research has been the design of "sanitation sequences":
G. Gunnerson step-by-step improvements leading from one technol-
vol. 12Eow-Cost Water Distribution-A Field Man- ogy to another and designed to minimize costs over the
ual, by Charles Spangler. entire sequence. These enable a community initially to
select one of the low-cost technologies in the knowledge
The main purpose of this appraisal is to summarize that, as the community's socioeconomic status im-
the technical, economic, health, and social findings of proves, the technology can be upgraded without
the research, and to discuss the aspects of program wasting the initial investment. It is noteworthy that
planning necessary to begin implementation of the none of the sanitation sequences has conventional
findings. It is, therefore, directed primarily toward sewerage as its final improvement. In urban areas, the
planning officials and advisors for sector policy in and final upgrading is generally to a low-volume flush toilet
for developing countries. Although the focus is primar- connected to a vault that overflows into a small-
ily on sanitation options (because water supply technol- diameter sewer. From the user's viewpoint, the only
ogy is better known and understood), information on difference between this system and conventional
levels of water service is included because water use is a sewerage is the size of the toilet tank in the bathroom.
determining factor in waste disposal. Technical details Yet the cost savings, particularly if installation
and designs are presented in Appropriate Sanitation proceeds in stages, are significant. Over a thirty-year
Alternatives: A Planning and Design Manual, forth- period the total present value cost of this alternative
coming as a complement to this volume. system is about one-half that of conventional sewerage.
The study presents the results of two years of field Its environmental cost is also likely to be significantly
studies undertaken by the World Bank in thirty-nine lower than that of sewerage because its eventual waste
communities in fourteen countries of the developing discharge is less. As this example indicates, the critical
world. A bibliographic search was initially conducted element in an economic solution to providing sanitation
for information on nonconventional options, but only is the reduction of nonessential water use. (Toward this
about 1 percent of the published technical literature on end, work is now underway to adapt water-saving
wastewater related to technologies other than sewer- showerheads and other appliances for use in develop-
age. Case studies carried out by local engineers, ing countries.) A corollary to this conclusion is that
economists, and behavioral scientists thus formed the schemes for water supply, with or without sanitation,
backbone of the research. should explicitly consider, in the design and cost
The first and most important finding of the case comparison of alternative service levels, the require-
studies was that there are many technologies between ment to dispose of the wastewater created.
the unimproved pit privy and conventional sewerage In addition to these technical findings, the research
that can be recommended for replication on a wide has produced a new and promising approach to the
scale. In all, five types of household (on-site) systems problem of linking potential health benefits to improve-
and four types of community systems were identified, ments in environmental sanitation. Rather than
xi
tackling yet again the intractable problem of quantify- portant for all technologies and never accounted for less
ing health benefits, this research focused directly on the than 45 percent of total household costs on an annual
transmission process of excreta-related disease and the basis; the latter was most important for sewerage and
relation of that process to the various sanitation septic tank systems. Where the economic cost of water
alternatives. The Ross Institute of Tropical Hygiene of is high, the payoff from designing systems with low
the London School of Hygiene and Tropical Medicine requirements for flushing water is large.
was contracted as part of this study to develop an The findings and recommendations of this appraisal
environmental classification of excreta-related infec- are based on surveys of relevant literature (see
tions that, together with a basic understanding of the Feachem and others, Sanitation and Disease, and
factors important in disease transmission, would enable Rybczynski, Polprasert, and McGarry, Low-Cost
the planner and engineer to maximize the health Technology Options), an evaluation of sociocultural
benefits of whatever technology is chosen. The means of factors (see Elmendorf and Buckles, Sociocultural
so doing include both the incorporation of specific Aspects of Water Supply), detailed field studies (see
design features and the supplementation of "hardware" Kuhlthau, Country Studies, and Lauria, Kolsky, and
with precisely directed educational campaigns for Middleton, Low-Cost Design), and the personal
users. [In the process of developing the environmental observations, experience, and advice of colleagues in
classification, Dr. Richard G. Feachem and others at the World Bank and other institutions. Because the list
the Ross Institute conducted a comprehensive review of of contributors is so large, only a few can be mentioned.
relevant literature and have produced a unique We wish to acknowledge, in particular, the support
reference work on the subject (Sanitation and Disease, given to this project by Yves Rovani, director of the
Part One) as well as an original and insightful analysis Energy, Water, and Telecommunications Department
of the relation between sanitation and excreta-related at the time the research was done and currently director
infections (Sanitation and Disease, Part Two and the of the Bank's Energy Department, and the valuable
references therein).] review and direction provided by Kim Jaycox, chair-
That alternative technologies exist and that they can man of the Project Steering Committee. Advice and
be designed to maximize health benefits still leaves the expertise in particular areas were freely provided by
planner with two important questions: what do the Jerry Warford and Harold Shipman, two of the early
technologies cost, and what complementary inputs do supporters of the project, and by William Cosgrove, Art
they require for successful implementation? The costs Bruestle, Fred Hotes, Johannes Linn, Ragnar Overby,
collected from a statistically based, case-study ap- John Courtney, and Charles Weiss. In addition, David
proach such as this one are bound to vary widely from Bradley and Richard Feachem of the Ross Institute of
one community to another even for identical technolo- Tropical Hygiene, D. Duncan Mara of the University
gies. When the problem is compounded by the fact that of Leeds, Gilbert and Anne White of the University of
no two observed pit privies, for example, were exactly Colorado, and Mike McGarry of the International
alike in their design or construction, it is obvious that Development Research Centre helped us considerably
precise measures of cost sensitivities cannot be in shaping our approach to the health and social aspects
obtained. Yet, by applying a consistent methodology to of the study and in developing the algorithm for
all case-study calculations and by deriving economic technology selection.
rather than financial costs, a broad cost comparison of Special thanks are due to the field consultants whose
different technologies was possible. tireless efforts to obtain and evaluate information
The nine technologies studied formed three distinct under diverse, and sometimes difficult, conditions
cost groupings. Five of them cost less than $100 made possible our empirical analysis. Their individual
annually per household (including both capital and contributions are acknowledged in the Appropriate
recurrent costs); two technologies cost between $150 Technology publications for which they were responsi-
and $200 annually per household; and two (septic tanks ble, but we would like to extend our particular thanks to
and sewerage) cost more than $300 annually per Kenneth Iwugo, who was responsible for the case
household. (All cost figures in the study refer to 1978 studies of Nigeria, Ghana, and Zambia; Ng Kin Seng,
U.S. dollars.) The ratio of lowest to highest cost of the who did the work on Malaysia and the island of Taiwan;
systems was 1:20. S. S. Soesanto for the excellent work of her team in
The two most important influences on total house- Indonesia; Dong Min Kim for his Korean study; Mary
hold costs were factors that have often been ignored in Elmendorf and Chuck Pineo for their work in Nicara-
engineering analysis: on-site household costs (for ex- gua; Samir El Daher and Beshir Mohammed El Has-
ample, internal plumbing) and the cost of flushing san, who undertook the Sudan study; Shohei Sata and
water for water-carried systems. The former was im- Katsuyoshi Tomono of Nihon Suido Consultants for
xii
their important work on the Japanese cities; Raphael in coordinating the graphics and other aspects of this
Rodriguez, who undertook the work on Colombia; publication with those of the other volumes in the
and Mike Blackmore and his team in Botswana. In Studies of Water Supply and Sanitation series is greatly
addition, Mei-Chan Lo and Robert T. C. Lee, both appreciated.
of Taiwan, were instrumental in helping us evaluate Finally, we owe a special thanks to our spouses-
the potential for wider replication of the interesting Nelly Kalbermatten, Ian Harvey, and Betty Gun-
intermediate technologies for sanitation that were nerson-who endured the extra travel and long hours
studied there. Harvey Ludwig and Saul Arlosoroff that this research project entailed.
assisted us in the evaluation of various technologies.
This book could not have been produced without JOHN M. KALBERMATTEN
the dedication and cooperation of the secretarial staff: DEANNE S. JULIUS
Margaret Koilpillai, Julia Ben Ezra, and Susan Pur- CHARLES G. GUNNERSON
cell. David Dalmat and Sylvie Brebion's efficiency
Acronyms and Abbreviations
AIC Average incremental cost PF Pour-flush (toilet)
BARC Beltsville Agricultural Research Center (U.S. PVC Polyvinyl chloride
Department of Agriculture, Beltsville, ROEC Reed Odorless Earth Closet
Maryland, U.S.A.) TACH Total annual cost per household
BOD Biochemical oxygen demand VIDP Ventilated improved double-pit (latrine)
BOD5 Five-day BOD (by the standard test) VIP Ventilated improved pit (latrine)
DVC Double-vault composting (toilet)
Appropriate Sanitation Alternatives
A Technical and Economic Appraisal
I I
1
An Overview
A CONVENIENT SUPPLY of safe water and the sanitary ing countries have adequate sanitation services; that is,
disposal of human wastes are essential ingredients of about 630 million out of 1.7 billion people.' Population
a healthy, productive life. Water that is not safe for growth will add to this figure in the 1980s another 700
human consumption can spread disease; water that million people who will have to be provided with some
is not conveniently located can reduce the productive means of sanitation if the goal of the International
time and energy of the water carrier; and inadequate Drinking Water Supply and Sanitation Decade-ade-
facilities for excreta disposal reduce the potential quate water supply and sanitation for all people-is to
benefits of a safe water supply by transmitting path- be achieved. A similar number of people, about 2
ogens from infected to healthy persons. Over fifty billion, will require water supply by the same date.
infections can be transferred from a diseased person Thus, approximately half a million people daily, from
to a healthy one by various direct or indirect routes now until 1990, will need to be provided with water and
involving excreta. sanitation services.
One of the fundamental problems in meeting this
Water Supply and Sanitation goal is the high cost of conventional sanitation services.
in Developing Countries General estimates based on 1978 per capita costs
indicate that up to $60 billion would be required to
Coupled with malnutrition, these excreta-related provide water supply for everyone, and from $300 to
diseases take a dredfutllnev$600 billion would be needed for sewerage.2 Per capita
especially among children. For example, in one Middle investment costs for the latter range from $150 to $650,
eastercilyaountry chald. Fof thexpldre,n bornalve die an amount totally beyond the ability of the beneficia-
Eastern country half of the children born alive die t
before reaching the age of five as a result of the ries to pay.
combine effects of disease andmalnutrition. In con- In industrialized countries, the standard solution for
combined effects of disease and malnutrition. In con- th
trast, only 2 percent of the children born in the United sanitary disposal of human excreta is waterborne
Kingdom die before reaching their fifth birthday. It is sewerage. Users and responsible officials have come to
invariably the poor who suffer the most from the view the flush toilet as the absolutely essential part of
absence of safe water and sanitation because they lack an adequate solution to the problem of excreta disposal.
not only the means to provide for such facilities but also This technology, however, was designed to maximize
the information on how to minimize the ill effects of the user convenience rather than health benefits. Conve-
theaninorm aondon wtini the il. l reffets the nience may be an important objective in developed
debilitating effects of endemic disease lower the pro- countries, but it has a lower priority in most developing
deiting peffect of enderm disease lower the pro countries. In fact, conventional sewerage has been the
such loss of productivity. result of a slow progress made over decades, even
centuries, from the pit latrine to the flush toilet, and the
Dimensions of the problem present standard of convenience has been achieved at
substantial economic and environmental costs.
To understand the magnitude of the problem, one The problem facing developing countries is a
only need consult the data collected by the World familiar one: high expectations coupled with limited
Health Organization (WHO) in preparation for the resources. Decisionmakers are asked to achieve the
United Nations Water Conference (Mar del Plata, standards of convenience observed in industrialized
Argentina, Spring 1977). These rough estimates show countries, but-given the backlog in service, the
that only about one-third of the population in develop- massive size of sewerage investments, and the demands
3
4 OVERVIEW
on financial resources by other sectors-they do not they have to press for sewerage because without it
have the funds to realize this goal. Sewerage could be public health will not be secure. Few sewer systems in
provided for a few, but at the expense of the vast developing countries are well maintained. Sewage
majority of the population. As a consequence, many treatment works commonly discharge effluents in a
developing countries have taken no steps at all toward condition little better (and in some cases worse) than
improving sanitation. The very magnitude of the task the incoming sewage. In any case, current plant design
has effectively discouraged action. concentrates on undoing the environmental problems
At the present time the first priority of excreta waterborne collection has created rather than on health
disposal programs in developing countries must be maintenance through pathogen removal. There is,
human health; that is, the reduction and eventual therefore, little realistic basis for the commonly held
elimination of the transmission of excreta-related dis- view that Western sanitation techniques are the appro-
eases. This health objective can be fully achieved by priate solution for developing countries. Rather, re-
nonconventional sanitation technologies that are much education of engineers to design for maximum health
cheaper than sewerage. The goals for the International benefits, and to consider the whole range of available
Drinking Water Supply and Sanitation Decade of the technologies, is essential.
1 980s intentionally do not specify sewerage, but call for Most municipalities in developing countries have
the sanitary disposal of excreta-leaving the chosen difficulty in attracting and retaining well-trained staff,
disposal method to the discretion of individual govern- and in consequence municipal services suffer. The
ments. Similarly, objectives of the Decade include an potential for self-help in conventional sewerage is,
adequate supply of safe water, but do not specify the however, minimal. The adoption of low-cost technolo-
methods to be used to achieve the goal. The challenge of gies can capture the strong desire of most people to
providing as many people as possible with the required improve their living conditions, and this motivation can
facilities is to find techniques to achieve these objec- be put to good use. But this implies a change in the role
tives with the resources available. of the municipality; it must become an active promoter
and educator because experience makes it abundantly
The constraints clear that technologies imposed on people without
adequate consultation are likely to fail or go unused.
The principal constraints to the successful provision
of sanitation facilities in developing countries are lack A glimpse of a solution
of funds, lack of knowledge about nonconventional
sanitation technologies, and weak institutions with few Given these constraints, it is not surprising that levels
trained personnel. There is no foreseeable way that of sanitation service in developing countries have re-
waterborne waste disposal, with an average investment mained low. A major effort is needed to identify and
cost of around $300 per person, can be made affordable develop alternative technologies for sanitation that are
in countries in which annual per capita income averages appropriate to the conditions in developing countries
less than that amount. In addition, and implicit in the and are designed to meet health requirements at a cost
decision to provide sewerage, is a decision to provide a affordable to the user. Clearly, the solutions also must
water connection to each house. About 40 percent of the reflect the communities' preferences.
water from this connection will be used for no essential The identification and design of appropriate excreta
purpose but to flush away wastes. Even in the unlikely disposal systems does not require the invention of new
event of the developed countries' providing massive processes or devices. Rather, it calls initially for a
grant funds towards the initial cost of installing sewer- review of the historical development of the present
age in the developing world, the costs of operating and technology, a reexamination of the decisions leading to
maintaining sewer systems and of satisfactorily dispos- sewerage, and the design of improvements to eliminate
ing of the sewage would be prohibitive. Lower-cost problems that caused the abandonment of earlier, low-
solutions have to be found for the majority of people. cost solutions. An examination of how sewerage came
The lack of interest in sanitation technologies other about reveals three facts clearly. First, waste disposal
than sewerage is in part because of the standardized went through many stages before sewerage. Second,
education of most planners and engineers in developing existing systems were improved and new solutions
countries. Engineers are trained in sophisticated (and invented whenever the old solutions were no longer
intellectually stimulating) advanced technology that is, satisfactory. Third, improvements have been imple-
in a sense, self-perpetuating: sewer systems lead to high mented over a long period of time and at substantial
water consumption and the attendant problems of cost. Sewerage was not a grand design achieved in one
source development and effluent disposal. Planners feel giant step but is the end result of progressively sophisti-
OVERVIEW 5
cated solutions. It took industrialized countries over a proportions"4 or "induced bias."5 Schumacher's book
hundred years to achieve their present status in a close served to bring some of the basic ideas into public view.
matching of needs and the economic capacity to take There is no concise and universally correct definition
care of them. With the benefit of hindsight, it should be of technological appropriateness; the concept is a rela-
possible to correct not only some of the shortcomings of tive one, which can only be applied within a particular
previous solutions, but also to develop a sanitation context. The standards for determining the appropri-
system that can be further improved, step by step, to ateness of technology are related to the developmental
meet both the user's requirements and economic capac- goals of the country making the choice and to the
ity to pay for improvements. circumstances of the technology's use. Various rules of
What is needed is a sequence of sanitation improve- thumb have been suggested that call for low capital
ments, designed from the outset to provide maximum intensity, simplicity of operation, use of indigenous
health benefits while minimizing costs over the long resources, and so forth, but they are of limited use in
run. If sanitation facilities are to be used, each step of comparing diverse technologies, which would rank
the sequence must consider consumers' preferences and differently according to each of these criteria, and they
customs of personal hygiene. In fact, sequenced sanita- are not universally appropriate for all developing coun-
tion is likely to be more successful than the immediate tries.
installation of sewers has been because it allows the The operational definition used in this study is really
user to progress as he sees fit, to whatever level of an abbreviated description of the process of determin-
convenience he desires and at his own speed, in a ing which technology is appropriate in a particular
reflection of his personal preferences and capacity to case. An appropriate technology is defined as a method
install, operate, and pay for the facility. or technique that provides a socially and environmen-
Fortunately, low-cost alternatives to sewerage exist tally acceptable level of service or quality of product
and work well. When properly constructed and main- with full health benefits and at the least economic cost.6
tained, they provide all the health benefits of sewerage This "definition" immediately provokes questions.
and have fewer adverse environmental effects. They How does one judge social or environmental acceptabil-
are, in many cases, technologies that had been used for ity? What is the economic cost of a process? There is an
many years in developed countries but were abandoned intuitive understanding of the words themselves, but
rather than improved as those countries grew more their application is not straightforward. This study
prosperous. They may not be applicable to parts of the looks in detail at the process of identifying appropriate
dense, westernized, metropolitan centers of the devel- sanitation technology from the technical, economic,
oping world, where sewerage may remain the most health, and social perspectives. The basic philosophy is
appropriate technology, but they are ideally suited to that only those technologies that pass all these tests are
rural areas, small towns, and metropolitan fringe areas, appropriate. The operational definition incorporates
which closely resemble the environment for which they long-run benefits and costs by using life-cycle costing
were originally developed. Their failures are usually and by paying particular attention to the technical
attributable to poor design, inadequate education of potential for upgrading each alternative as the incomes
users, or lack of maintenance-problems that plague and aspirations of the users grow over time.
sewerage systems as well but can be overcome in
developing countries if increased emphasis and atten- The selection process
tion are given to improving health and sanitation.
The process of selecting technology begins by
identifying all the technological alternatives available
for providing the good or service desired (in this case,
An Operational Definition sanitation). Within that set of possibilities there will
of Appropriate Technology usually be some technologies that can be readily
excluded for technical, health, or social reasons. For
A large body of literature has developed in recent example, septic tanks requiring large drainage fields
years on the choice of appropriate technology, would be technically inappropriate for a site with high
particularly in the manufacturing and agricultural population density. Similarly, a composting latrine
sectors. The surge of interest in this topic dates from the would be socially inappropriate for people who have
publication of E. F. Schumacher's book Small Is strong cultural objections to the sight or handling of
Beautiful in 1973.3 Before 1973, the theory of techno- excreta. Some technologies may require institutional
logical choice was written about mostly by economists support that is infeasible in the given social environ-
and was concealed in technical jargon such as "factor ment. Once these exclusions have been made, the range
Figure 1-1. Recommended Structure of Feasibility Studies for Sanitation Program Planning
Sanitary Engineer and Economist Behavioral Scientist Community
Public Health Specialist
Examine physical and Collects Consults with communtAdvises on
environimental coniditionis mareooncto collect informationprciean
Stage 1 and establish community nacoecrmionmnd prefnces practices anc
health profile onformaion an practices preferenzces
I ndentify and cost Identifies economic Linsts sutoaland
Stage tehnically and medicallv institutioially
faible alternatives cosrit n iisfeasible, alternattves
Prepares short li5t Identifies community's
Stage 3 of feasible alternatives e contribution and level - Advises
of feasible alternatives of affordability
Prepare final design Agrees otn typical layouts
Stage 4 and estimate unit cost and local community Advises
of feasible alternatives \ / participation
Sta e S \>| ~~~~~~~~~~Prepare.s financialt co'sling|J
Stage offeasble alternative
sy.stern.s\
Crommunity selects
Stage 6 preferred alternative
OVERVIEW 7
of technically and socially feasible alternatives that estimates for those technologies that have passed tech-
provide full health benefits remains. For these technol- nical and social tests and selects the least-cost alterna-
ogies, cost estimates are prepared that consider their tive for each. As the fourth step, the engineer prepares
real tesource cost to the economy. As described in final designs and unit costs for these choices. At this
chapter 3, this may involve adjustments in market point the social information collected in stage I should
prices to counteract economic distortions or to reflect be used to determine, for example, the siting of the
developmental goals such as the creation of employ- latrine on the plot, the size of the superstructure, the
ment.' Least-cost solutions for each technology are materials to be used for the seat or slab, and other
determined. On the basis of these economic costs and details whose technical and economic import may be
discussions with government planners, financial costs low but which make a major difference in the way the
are prepared for all least-cost solutions. Those alterna- technology will be accepted and used in the community.
tives clearly outside the bounds of affordability for The final designs should also incorporate features
consumers are excluded. Because the benefits of vari- necessary to maximize the health benefits expected
ous sanitation technologies cannot be quantified, it is from each technology. Final designs are used in the
impossible for the economist to do more than exclude fifth stage to determine financial costs (based on the
various alternatives. A single least-cost alternative availability of national and municipal funding), includ-
cannot usually be recommended because there is no ing how much the user will have to pay for construction
way of quantitatively comparing benefits. The final and maintenance of each design. Any technology whose
step in identifying appropriate sanitation technology total financial cost is more than 10-20 percent of user
must rest with the eventual beneficiaries. Those alter- income probably should be excluded as financially
natives that have survived technical, health, social, and unaffordable. The final step is for the behavioral
economic tests are presented to the community with scientist to present and explain the alternatives and
their corresponding financial price tags, and the users their costs to the community for final selection.
must decide for which level of service they are willing
to pay.8 Comparison with the traditional approach
How the technical, health, social, and economic
aspects of technological choice are actually coordinated The process above contrasts with that of the typical
is shown in figure 1- 1, although the stages in the figure feasibility study. The conventional team conducting
should not be interpreted too literally. A technology feasibility studies is heavily weighted with engineers. It
may fail technically if the users' social preferences may contain a financial analyst, but rarely an econo-
militate against its proper maintenance. The economic mist, and almost never a behavioral scientist. The
cost of a system is heavily dependent upon social factors alternative technologies considered are usually only a
such as labor productivity as well as upon technical small subset of the group discussed in this report, and in
parameters. Because of these relations between the many cases the terms of reference of the study (written
various boxes in figure 1-1, there must be a close by other engineers) limit the selection to waterborne
working association among the different actors in the sewerage with several collection configurations and
planning process. treatment alternatives. Thus the selection process de-
For simplicity, it is assumed that separate individuals scribed in figure 1-1 is short-circuited and moves
or groups are responsible for each part, although in directly through technical criteria to final design. The
practice responsibilities may overlap. In stage 1 of conventional study team then prepares estimates of
figure 1-1, each specialist collects the information financial costs and writes its report.
necessary to make his respective test for exclusion. For The main problems of this customary process are
the engineer, health specialist, and behavioral scientist, obvious from a comparison with the methods set forth
this data collection will usually take place in the in this study. In the conventional procedure, the most
community to be served. The economist will talk with appropriate technologies may never get considered. No
both government and municipal officials to obtain the checks are made to ensure that the technical solution
information necessary to calculate shadow rates and to designed and costed is socially acceptable. By excluding
determine the availability of grant funds or other a meaningful economic comparison, the usual method
means of subsidy. The engineer, health specialist, and makes no guarantee that the solution offered is the one
behavioral scientist will then apply the information of least cost for the economy. The decisionmakers are
they have collected to arrive at preliminary lists of presented at the end with a proposal that has not taken
technically, medically, and socially feasible alterna- into account their own economic priorities or the ability
tives. In the third stage the economist prepares cost to pay of their constituents, the ultimate beneficiaries.9
8 OVERVIEW
The framework suggested in this report for the 5. C. Kennedy, "Induced Bias in Innovation," EconomicJournal,
identification of appropriate technologies is probably vol. 74 (September 1964), pp. 541-47.
more time intensive than that of traditional feasibility 6. A more rigorous definition would be the technology for which
analysis. It also requires the recruitment of additional the net present value of the stream of health and environmental
personnel. Thus, a clear case must be made for its benefits, subject to a constraint on social acceptability, is maximized.
superiority in choosing appropriate technologies, and it The difficulty of quantifying health and environmental benefits,
must be shown that the cost of choosing an inappropri- however, prevents such a definition from being operationally useful.
ate technology is sufficiently high to warrant a more 7. An ideal analysis would go beyond economic costing to include
costly selection process. The case studies of sanitation income-distributional factors by calculating social costs. Distribu-
systems in thirty-nine communities, which form the tional weights, however, cannot be taken into account explicitly in
basis of this report, lead us to believe that there is a very this analysis because benefit quantification is not possible. This is not
high cost, both in wasted resources and in poorer a significant limitation because the major concern of this study is to
community health, associated with the imposition of identify technologies that are specifically appropriate for the rural
inappropriate sanitation technologies. Part One of this and urban poor. The study's case studies themselves were chosen to
inappopriae saitatin tehnoloies. art ne ofth embody this concern.
appraisal presents the detailed findings of the commu-
nity studies. 8. Because the consumer is presented with financial rather than
economic costs, it is important that economic cost ranking of the
technologies be preserved in deriving financial costs. This may
Notes to Chapter 1 preclude, for example, full construction grants for all technologies
regardless of relative construction costs.
I. "Billion" is equivalent to "thousand million." 9. Blame should not necessarily be placed on the consulting firms
2. All cost figures in this study are in 1978 U.S. dollars. See who prepare such conventional studies. Often they are guilty of no
chapter 3 for their derivation. more than following current practice in a highly competitive field,
3. E. F. Schumacher, Small Is Beautiful (New York: Harper and and they must work within the constraints of their terms of reference.
Row, 1973). A number of firms, in fact, are already implementing some of the
4. R. S. Eckaus, "The Factor Proportions Problem in Undevel- recommendations of this report and routinely use multidisciplinary
oped Areas," American Economic Review, vol. 45 (September 1955), teams in their work. The obstacles to the choice and adoption of
pp. 539-65. appropriate technologies are discussed in chapter 6.
Part One
Analysis of Field Study Results
Technical and Environmental
Assessment
INVESTIGATIONS OF SANITATION SYSTEMS on sites in When the pit is about three-fourths full, the superstruc-
thirty-nine communities around the world have pro- ture and squatting plate are removed and the pit is filled
vided a wealth of practical design and operational data up with soil from a new pit dug nearby.
upon which a technical assessment of various sanitation Most of the seven pit latrines evaluated in this study
alternatives may be based. Although many variations were of the simple, unimproved variety and conse-
of similar systems were observed, this chapter classifies quently had both odor and insect (flies and mosquitoes)
all of the technologies studied into five types of house- problems. These undesirable features were almost com-
hold systems and four types of community systems. The pletely absent in the ventilated, improved pit (vip)
essential features of each are described, the technical latrine and the Reed Odorless Earth Closet (ROEC)
requirements and environmental limitations are dis- observed in southern Africa.
cussed, and an assessment is made of the potential for
upgrading and widely replicating each. The cost and
health implications of the technologies are presented in
the following two chapters.I For a generic classification VIP latrines
of the various sanitation systems, see figure 2-1. A
summary of the data on population and service levels In a vIP latrine (figure 2-1, no. 5), the pit is slightly
characteristic of some of the communities studied is displaced to make room for an external vent pipe. For
shown in tables 2-1 and 2-2. maximum odor control the vent pipe should be at least
150 millimeters in diameter, painted black, and located
on the sunny side of the latrine so that the air inside the
Household Sanitation Systems pipe will heat up and create an updraft. (Indications are
that painting the pipe black may increase the ventilat-
Pit latrines, pour-flush (PF) toilets, composting toi- ing effect.) If the vent pipe is letting enough light into
lets, aquaprivies, and septic tanks for use in individual the pit, and if the superstructure is fairly dark, flies will
homes are the major types of household sanitation try to escape through the vent rather than back into the
systems. The distinguishing feature of these, compared superstructure. Covering the vent pipe with a gauze
with the community systems discussed in the next screen will prevent flies from escaping through that
section, is that they require little or no investment in route and thus minimize the health hazard from these
facilities outside individual homesites. insects.2 Where the user prefers a solid superstructure
that cannot be moved, or where space is not available
for moving a vIP latrine, a modification-a ventilated
Pit latrines improved double-pit (VIDP) latrine-can be used. The
VIDP latrine contains two pits, which are dug side by
By far the most commonly observed technology side and are covered by the same superstructure. Use of
around the world, particularly in rural areas, is the pit the two pits alternates, with the squatting plate being
latrine (figure 2-1, no. 3). In its most elementary form, moved from the full to the empty pit as necessary. The
a pit latrine has three components: the pit, a squatting full pit is emptied not less than twelve months after last
plate (or seat and riser), and the superstructure. The pit use to be ready for renewed use when the second pit is
is simply a hole in the ground into which excreta fall. full.
11
12 ANALYSIS OF FIELD STUDY RESULTS
Table 2-1. Water Service Levels for Selected Study Communities
Water service level
Population Types of service, Liters per Cubic meters
Community Total Per hectare Percent Percent capita daily per hectare daily
East Asia
1 (rural) 56.000 5.2 13 (W) 87 (H) 271 1.4
2 (resort) 57,000 4.2 28 (W) 72 (H) 208 0.9
3 (suburban) 103,000 79.0 1 (W) 99 (H) 268 21.1
4 (urban) 1,426,000 24.0 3 (W) 97 (H) 340 8.2
5 (rural) 85,000 37.8 10 (0) 90 (H) 136 5.1
6 (urban) 175,000 26.9 80 (0) 20 (H) 108 2.9
7 (urban) 342,000 25.8 17 (0) 83 (H) 125 3.2
8 (rural) 285 n.a. 12 (W) 88 (H) 1(0 n.a.
9 (rural) 310 n.a. n.a. n.a. 40 n.a.
10 (urban) 141,000 4.2 23 (W) 77 (H) 143 0.6
Southeast Asia
11 (rural) 614 5.2 0 100 (H) n.a. n.a.
12 (urban) 2,000,000 407.0 0 100 (H) 41/67k 16.7/27.3b
13 (urban) 2,000,000 496.0 0 100 (H) 36/61h 17.9/30.2"
14 (urban) 5,000.000 9.0 0 100 (H) 45/60D 0. 40.5b
15 (urban) 5,000.000 582.0 0 100 (H) 31/62b 18.0/36.1I
16 (urban) 90,000 850.0 14 (S) 86 (H) 207 167.0'
17 (urban) 101,000 700.0 34 (S) 66 (H) 160 112.0'
18 (urban) 106,000 800.0 50 (S) 50 (H) 180 144.0c
Latin America
19 (rural) 196 n.a. 0 100 (H) n.a. n.a.
20 (rural) 800 n.a. 0 100 (H) 53 n.a.
21 (suburban) 18,000 n.a. n.a. 50 (H) 152 n.a.
22 (urban) 535,000 n.a. n.a. 90 (H) 341 n.a.A
23 (rural) 12,000 30.0 0 100 (H) n.a. n.a.d
East and West Africa
24 (urban) 20,000 n.a. n.a. n.a. 177' n.a.
25 (urban) 114,000 n.a. n.a. n.a. n.a. n.a.
26 (urban) 250,000 n.a. n.a. n.a. n.a. n.a.
27 (urban) 500,000 n.a. n.a. n.a. n.a. n.a.
28 (urban) 500,000 n.a. n.a. n.a. n.a. n.a.
29 (urban) 650,000 n.a. 7 (0) 93 (S) 20 n.a.
North Africa
30 (rural) 4,000 11.0 n.a. 95 (H) 5(0 0.6
31 (rural) 24,000 12.0 0 100 (S) 60 0.7
32 (urban) 250,000 107.0 0 100 (H) 70 7.5
33 (urban) 350,000 73.0 n.a. 97 (H) 10( 7.3
n.a. Not available.
a. Percentages of population served by house connection (H), standpipe (S), vendor (V), well (W), or other service (0).
b. Paired values indicate liters per capita daily in dry/rainy season.
c. High values are for areas of heavy year-round afternoon rains and runoff.
d. Piped supplies available but not used because of water's disagreeable taste and color.
e. In more detail: 12 liters per capita daily for standpipe; 74 liters per capita daily for low-cost housing; 122 liters per capita daily
for medium-cost housing; 434 liters per capita daily for high-cost housing.
ROECs breeding. The chute must therefore be cleaned regu-
Another successful variation of the pit latrine is the larly with a long-handled brush or a small amount of
ROEC (figure 2-1, no. 4). Its pit is completely displaced water. The advantages of the ROEC over the VIP latrine
from the superstructure and connected to the squatting are that its pit can be larger and thus have a longer life
plate by a curved chute. A vent pipe is provided, as in (because the superstructure is displaced), the users
the VIP latrine, to minimize fly and odor nuisance. A (especially children) have no fear of falling into its pit,
disadvantage of the ROEC, however, is that the chute is and it may be more acceptable in some societies
easily fouled, thereby providing a possible site for fly because the excreta cannot be seen.
TECHNICAL AND ENVIRONMENTAL ASSESSMENT 13
Table 2-2. Sanitation Systems for Selected Studv Communities
Sanitation systems present (*) or utilized (percent)
Household svstems
On-site Communal
Community Co systems
(see table latpine Aqua-
2-] for latrinee privy Over-
population Pit Contin- Aqua- Septic Off-site septic hung
data) latrine ROEC VIP Batch uous PF privy tank Sewer Vault Bucket tank latrine
East Asia
1 6 15 59
2 10 81
3 1 7 44 44
4 1 15 41 41
5 66 34
6 57 29 14
7 1 70 29
8.9 100
10 1 74
Southeast Asia
11 13 87
12 60 40
13 7 93
14 7 57 36
15 57 20 23
16 1 46 49 4
17 34 56 10
18 66 15 19
Latin America
19 30
2(0 60
21 50 15 29
22 27 73
23 35 14 9
Africa
24 * * *
25 * *
26
27 k
28
29 * *
31) 98 1 1
31 70 31)
32 84 1 1
33 30 70
Note: ROFC, Reed Odorless Earth Closet; vii', ventilated improved pit latrine; 'T, pour-flush toilet.
Pit latrines are most suitable in low- and medium- the ground. In addition, if nearby groundwater is used
density areas (up to about 300 persons per hectare) for drinking, pit latrines should not be placed within 10
where houses are single storied.3 It is customary to place meters or so of the well. If the soil is fissured, the
the latrine 3 to 5 meters from the house. Where pollution from the latrine will be more extensive, and
appropriate measures for odor and fly control are taken this distance may need to be increased.
(as in VIP latrines and ROECs), the latrine may be Where these environmental limitations do not apply,
placed adjacent to the house. In sandy soil the pits may or where the disadvantages of other systems outweigh
need to be partially lined to prevent collapse, and where those of pit latrines, the VIP latrine and ROEC are
the ground is rocky they may be difficult to dig. In areas suitable for replication. Their technical designs are
that have a high water table or that are prone to good; they can easily be upgraded to PF toilets; their
flooding, the latrine may need to be raised partly above costs are low; and their potential for health benefits is
Figure 2-1. Generic Classification of Sanitatiotn Systems
Sliln-^ v,tefll
|()n->itc |r~~~~~~~~~~~~)II sitc or 0(11-mitv
| DrV | Wt _~~~ ~ ~ ~~ We( We WE |DIrv
I. (OcrOLtng lat rmle 8. 1 -r1turfInsil (,I) -arrui&c 'atiki- 14 1ou-ohenl ir,,ci,ernt-tIth1 . 17 (n d tnunv r i ecc Iri Vtlrtlt in)" -eLacnt tanlk
2 I rnch lamtrurt w-yv onakata vr cme r 1t. Vault. anu-al erromv:, tru-k.
3 Pit latimmt 9) qt latrine. .aqunprie . ommaki 15 1 mnt-vmmiuteeistcrI-tlttnh. nnt a rl
4. R-ed )dorl-e Inrtb ( thue wan tinaplivy, oA-:nka Ys . r 201 Buncket Lan,,-
(1n: ) Int 1: laltlilC. p[rtne tIllrk. mimilt sew-I 21. M-hltaical bucket kltrine
5. Vetrtirtal itrtl-ra pit I 1 Sit lage-fitnelt h a. u r - I tw nolnlmt eisten tt-pt1]ttt
wsoka,m scptic tannk soakai-iu a r
Im Ittleti-u])i^g lninc 1a2t Slnltgc-ltla.sh scpti, l:mk. ew ke
7. (Conttnnmntn -enmllptoing lwyrinc -aka-y
1.1 ('tr^<sclilioInait septic tank
13 Saw 12 exccpt on-lte ntun) ciselrN n tnllt 14, 15, 16 Santte ia, -e-rsponttditng Cnttlirntaltlon in 8 to 12. 17 S-e stnit n.r.t Irrinnakint itlnd tcl
-cxcpj n 11C)r in>ed cistanl withlo I-w I1llc i11n,l
IR 19 20 21
Q, Move'rient ttf liqmrids: *. irrnvemenr tl nstlices
Sounrnt: hlic World 1.ank. Watrer SutpplI anntd Waste I)itmsn.el. Pn crt\ antd B.asic Needs Senies (Waishinileton. I) ( Septembier 190()).
TECHNICAL AND ENVIRONMENTAL ASSESSMENT 15
high. When introduced with an appropriate educa- known as a "multrum." The composting pit, which is
tional program for new users, they can be very effective immediately below the squatting plate, has a sloping
at providing sanitation services affordable to the major- floor with inverted U- or V-shaped channels suspended
ity of people in rural and urban fringe areas. above it to promote aerobic conditions in the chamber.
Grass, ash, sawdust, or household refuse are added to
PF toilets the pit to attain the necessary carbon-nitrogen ratios for
composting to occur. Moisture must be carefully con-
There are two types of PF toilets. The first is a simple trolled. The material slowly moves down the sloping
modification of the unimproved pit latrine in which the floor and into a humus vault from which it must be
squatting plate is made with a 25-millimeter water seal. removed regularly.
Approximately 1-2 liters of water (or sullage) are If the temperature in the composting chamber is
poured in by hand to flush the excreta into the pit.4 This raised by bacterial activity to above 60 C (degrees
type of PF toilet is especially suitable wherever water is Celsius), all pathogens in the excreta will be destroyed.
used for anal cleansing. The second type of PF toilet, In the units observed in southern Africa, however, the
which was observed in Indonesia and Colombia, has a temperatures inside were only slightly above ambient.
completely displaced soakaway pit (figure 2-1, no. 8) In addition, continuous composters were extremely
that is connected to a PF bowl by a short length of 100- sensitive to the degree of user care: the humus had to be
millimeter pipe. This type of PF toilet can be installed removed at the correct rate; organic matter had to be
inside the house because it is free of odor and insect added in the correct quantities; and only a minimum of
problems and its toilet fixture is displaced from the pit. water could be added. Even if all these conditions are
When the pit is full, a new one is dug and the latrine is met, fresh excreta may occasionally slide into the
connected to it. Alternatively, and especially in densely humus pile and limit the compost's potential for safe
populated areas, a vault may replace the pit and be reuse. The conclusion of this study, therefore, is that
emptied by vacuum cart (see figure 2-1, no. 18). The continuous composting toilets should not be recom-
displaced PF toilet can therefore satisfy the aspiration mended for use in either the urban or the rural tropics.
for an "inside" toilet at low cost. In addition, as water Double-vault composting (DVC) toilets (figure 2-1,
use increases, the pit can be fitted with an outlet that no. 6) are the most common type of batch composting
connects to a drainfield or small-bore sewer system. toilet. They have two adjacent vaults; one of these is
This option is examined more fully in the discussion of used until it is about three-fourths full, at which point it
sanitation sequencing (chapter 9, the section "Sanita- is filled with earth and sealed and the other vault is
tion Sequences"). used. Ash and organic matter are added to the vault
The environmental requirements for PF toilets are before it is sealed to absorb odors and moisture. The
much the same as those for pit latrines. In addition, composting process is anaerobic and requires several
however, 3-6 liters per capita daily of water are re- months, preferably a year, to make the compost patho-
quired for flushing. Thus, in areas where water is gen-free and safe for use as a soil fertilizer or condi-
carried from distant standpipes or surface sources, the tioner.
pit latrine is probably a better choice until the commu- DVC toilets require some care by users to function
nity's level of water service is improved. The simple properly and thus are harder to introduce than VIP
technical design, low operational requirements, and latrines or PF toilets. They are unsuitable in areas where
high potential for upgrading of PF toilets make them an organic waste matter or grass are not easily available or
attractive technology for widespread replication in where the users do not want to handle or use the
many areas of the world. Their most severe limitations composted humus. These factors tend to restrict their
in practice are that users often do not use enough use to rural or periurban areas where users are likely to
flushing water or that the toilets can become blocked by have gardens and access to grass for the composting
solid materials used for anal cleansing. For these process. Even here, unless there is a strong tradition of
reasons, an educational program for users should ac- reusing excreta in agriculture, DVC toilets have no
company the introduction of these facilities into a new advantages-and in fact have major disadvantages-
area. over the VIP latrine.
Composting toilets Aquaprivies
There are two basic types of composting toilets: The conventional aquaprivy consists of a squatting
continuous and batch. The continuous composters (fig- plate above a small septic tank that discharges its
ure 2-1, no. 7) are developed from a Swedish design effluent to an adjacent soakaway (figure 2-1, no. 9).
16 ANALYSIS OF FIELD STUDY RESULTS
The squatting plate has an integral drop pipe that is solids settle to the bottom where they are digested
submerged in the water of the tank to form a simple anaerobically just as in the aquaprivy. Although the
water seal. As long as the water level in the tank is digestion is reasonably good-about 50 percent reduc-
properly maintained, odor and insect nuisance are tion in biochemical oxygen demand (BOD)-enough
avoided. In order to maintain the water level, the vault sludge accumulates so that the tank must be desludged
must be watertight and the user must flush sufficient every one to five years. The effluent is usually disposed
water into the tank to replace any losses to evaporation. of in subsurface drainfields. In impermeable soils either
The tank normally requires desludging when it is about evapotranspiration beds or upflow filters can be used,
two-thirds full, usually every two to three years. although there is little operational experience with
In practice, maintenance of the water seal has either of these systems in developing countries.
generally been a problem, either because users are Septic tank performance can be improved by various
unaware of its importance to the system or because they modifications-for example, the use of three (rather
dislike carrying water into the toilet. If the seal is not than two) compartments (figure 2-1, no. 10) or the
maintained, there is intense odor release, and fly and addition of an anaerobic upflow filter. This latter
mosquito problems abound. One African country modification requires further testing and evaluation
banned the building of aquaprivies because of such before its widespread application can be recommended.
problems. A variation on the conventional design, The former is a well-known modification that is par-
called the self-topping or sullage aquaprivy (figure 2-1, ticularly useful for systems in which excreta and
no. 11), was developed to overcome the problem of sullage are disposed of separately (as in PFlatrines). By
losing the water seal. A sink is located either inside the this modification excreta can be emptied into the first
latrine or immediately adjacent to it and is connected to compartment and sullage into the second, with the
the tank so that sullage is regularly flushed into the effluent discharged from the third. This arrangement
aquaprivy. Because this additional water necessitates a improves the settling efficiency of the wastes (including
larger soakage pit, sullage aquaprivies cannot be used the separation and inactivation of pathogens), increases
in urban areas where the soil is not suitable for the soil absorption of the effluent, and permits the
soakaways or where the housing density or water table effluent's limited reuse.
is too high to permit subsurface infiltration for effluent Septic tanks are suitable only for houses that have
disposal. In such cases it is possible to connect the both a water connection (necessary for the cistern-flush
aquaprivy tank to a small-bore sewer system, with toilet) and sufficient land with permeable soil for
eventual treatment of the sullage in a series of waste effluent disposal. They are an important sanitation
stabilization ponds. Desludging would still have to take option because they can provide a very high level of
place every two to three years. service to those who can afford it in a given community,
If properly maintained, the conventional aquaprivy without necessitating the commitment of community
is a sound technical solution to excreta disposal. How- funds for the construction of a sewerage system. Thus,
ever, it has no technical advantage over the PF latrine, as part of a sanitation package that can meet the needs
which is easier to build and maintain and costs less. In of all the members in a given community, septic tanks
addition, with its more sophisticated water seal the PF have a widespread potential for replication because,
latrine can be located inside the house and is more with proper soil conditions, they permit satisfactory
easily upgraded to a cistern-flush toilet (figure 2-1, no. excreta disposal even for users of cistern-flush toilets
15). The only comparative advantage of the aquaprivy (figure 2-1, no. 16).
is that it is less easily blocked if solid cleansing
materials are used or this material is thrown into the
vault. Thus, except in cases in which users are unwilling Community Sanitation Systems
to change such habits, the PF toilet should be preferred
to the aquaprivy. Bucket latrines, vault toilets, communal toilets, and
sewerage systems for communities are examined in this
Septic tanks section. All require both off-site facilities and a perma-
nent organizational structure with full-time employees
The final household system to be discussed is the to operate successfully.
septic tank. The conventional septic tank (figure 2-1,
nos. 12, 13) is a rectangular chamber, separated into
two compartments sited just below ground level, that
receives both excreta and sullage. During the one to The traditional bucket latrine (figure 2-1, no. 20)
three days of hydraulic retention time in the tank, the consists of a squatting plate and a metal bucket, which
TECHNICAL AND ENVIRONMENTAL ASSESSMENT 17
is located in a small vault immediately below the Vaults are suitable for medium-rise buildings in which
squatting plate. The bucket is periodically emptied by a excreta can be flushed down a vertical pipe into a
night-soil laborer or "scavenger" into a larger collec- communal vault at, or below, ground level. From the
tion bucket which, when full, is carried to a night-soil user's point of view, there is little difference between
collection depot. From there the night soil is normally vault and PF toilets; either can be built inside the house
taken by tanker to either a trenching ground for burial and no nuisance problems are likely. In addition, vault
or to a night-soil treatment works. toilets require a minimal amount of water (3-6 liters per
During the course of this study, bucket latrine capita daily) and are suitable for any type of soil and at
systems were observed in four countries in Africa and very high population densities. They can easily be
Southeast Asia. Problems of odor, insects, spillage, and upgraded into sewered PF toilets if at some stage it is
generally unsanitary conditions at all collection and desired to improve facilities for sullage disposal. Their
transfer points were ubiquitous. Although it is possible main disadvantage is one shared by all community
to make several improvements to the normal bucket facilities: the need for an institutional capability to
latrine system (for example, by providing facilities for organize the collection service and operate the treat-
washing and disinfecting the buckets, covering collec- ment facilities. The vault toilet systems for which
tion buckets with tightly fitting lids, or mechanizing the quantitative data were obtained in this study were
system, as shown in figure 2-1, no. 21), it is still difficult found in East Asia, where municipal institutions were
in practice to ensure that the system is operated well developed. Although the vault toilet system is
satisfactorily in developing countries. Even an im- technically sound, its widespread replication in other
proved bucket latrine system, therefore, is not one that parts of the world requires that it be subjected to
can be recommended for new installations. Existing prototype testing on a scale large enough to involve
bucket latrines should be improved as a short-term institutional development.
measure and replaced by some other technology in the
long term. In the high-density urban areas where
bucket latrines are most often found, the most likely Communal sanitation facilities
replacements for them include vault toilets and com- There are no unusual technical requirements for a
munal facilities.Thrarnouuultcnclrqiensfra
communal toilet. It may be a PF toilet, an aquaprivy, a
low-volume cistern-flush toilet, or some other type. If
Vault toilets shower, laundry, and clothesline facilities are not avail-
Vault toilets (figure 2-1, nos. 18 and 19), which are able in the houses, they may be provided at the
extensively used in East Asia, are similar to PF toilets, communal sanitation block. Such block facilities are
except that the vault is sealed and emptied by a vacuum normally designed with a capacity for twenty-five to
pump at regular intervals of two to six weeks. As with fifty persons per toilet compartment and thirty to fifty
the PF toilet, the vault may be built immediately below persons per shower. The most frequent problems en-
the squatting plate or displaced from it and connected countered in the communal facilities visited during this
to it by a short length of pipe. In the latter case, the study were inadequate water supply (for PF toilets) and
vault may be shared by adjacent houses with some poor maintenance. From a mechanical viewpoint, com-
savings in construction and collection costs. munal facilities may be the only low-cost alternative for
The vault itself need not be large. For example, for a providing sanitation to people living in very dense cities
family of six and with the vault being emptied every two with no room for individual facilities. The social and
weeks, the required vault volume is only 1.25 cubic institutional commitment to provide for their mainte-
meters, and about 0.6 cubic meters of night soil must be nance, however, can be a serious constraint.
removed each time the vault is emptied. The collection
cart or truck is equipped with vacuum tubing, which
may be as long as 100 meters to permit access to houses Sewerage
distant from a road or path. Disposal of the collected Conventional sewerage (see figure 9-5, d, in chapter
night soil is usually by trenching or treatment works 9) consists of a cistern-flush toilet connected to a
(see the section "Treatment Alternatives," below). network of underground sewers, which transport sew-
The vault toilet, emptied by either mechanically, age and sullage to a treatment or disposal facility. The
electrically, or manually powered vacuum pump, is an cistern-flush toilet is a water-seal squatting plate or
extremely flexible form of sanitation for urban areas. pedestal unit from which excreta are flushed away by
Changes in urban land use are easily accommodated by 10-20 liters of water stored in an automatically refill-
redefining the routes for collection tanker trucks. ing cistern connected to the household water supply.
18 ANALYSIS OF FIELD STUDY RESULTS
Sanitary sewers are usually made from concrete, consider sewerage only for those areas in which it is
asbestos cement, vitrified clay, or polyvinyl chloride clearly the most appropriate sanitation system for
(Pvc) pipe. Sewers are designed for transport by social and economic, as well as technical, reasons.
gravity of a maximum flow of up to four times the
average daily flow, and they need to be laid with a steep
enough slope to provide for a "self-cleaning" velocity of Factors Affecting Choice of Technology
about 1 meter per second to avoid blockages. A
conventional sewer system will require a 225-milli- Before the discussion proceeds to treatment, recla-
meter pipe (the minimum recommended size) to be laid mation, and disposal alternatives, a summary of the
at I in 90 slope, whereas a sewered PF system with a major technical and environmental factors that affect
vault to settle solids needs only a 100-millimeter pipe the choice of sanitation technology may be useful.
laid at a 1 in 200 gradient. Clearly, there is a
considerable difference in excavation and pipe costs Physical environment
between the conventional and small-bore sewers, which
will grow larger as the ground becomes rockier. Be- A group of maps is provided in this chapter to
cause small-bore sewers carry no solids, they also illustrate the range of constraints imposed by the global
require fewer manholes than conventional sewers. distribution of environmental variables (maps 1
The main advantage of a conventional system is the through 11) and some of the common tropical sanita-
high convenience to users it provides. The main techni- tion-related diseases (maps 12 through 19).
cal constraints are its large water requirement, the Information on the natural physical environment of
difficulty of the excavation in very dense areas or in an area will often permit the exclusion of certain
those with poor ground conditions (rocky soil, high options. Winter temperatures (maps I and 2) affect the
water table, and the like), the problem of laying sewers performance of waste treatment ponds, digesters, and
in fairly straight lines through areas of "unplanned" biogas units because each decrease of about 10 C or
housing without substantial demolition, the susceptibil- 18 F (degrees Fahrenheit) causes a decrease in bio-
ity of the pipe and joint materials to corrosion in hot chemical reaction rates by one-half. The distribution of
climates, and the blockage and extra maintenance precipitation (map 3) indicates the general levels of
problems that may arise during the early years follow- flooding, runoff, water table, and plant growth. The
ing construction of a sewer (when it is underused).5 A climate diagrams (maps 4 through 6) show details of
further problem of conventional sewerage is the envi- temperature and precipitation for specific locations
ronmental hazard created by point discharge of such considered in the present research. Horizontal scales on
large volumes of wastewater. This problem is reduced the inset charts are in months (January to December in
with (expensive) tertiary treatment plants, but devel- the northern hemisphere and July to June in the
oped countries are now discovering that even elaborate southern hemisphere); in each case summer is in the
treatment does not remove all of the environmental middle of the scale. Aridity index maps (maps 7
costs and consequences. through 9) show the ratios of potential evaporation to
Over the past three decades numerous attempts have precipitation and indicate climatic zones, particularly
been made to design and build sewer systems around those subject to desertification, in which the recovery of
the world. The success rate has not been high. The water, fertilizer, and energy from wastes is most impor-
majority of them have not gotten past the design stage tant. Soils and potential productivity are shown in maps
because of the failure to take into account the financial 10 and 1 1; the former reflects long-term effects of
constraints. Many of those built in developing countries climate, and the latter is a measure of land or aquatic
have had very serious problems with consumer accep- plant growth. Soil and weather allow for higher produc-
tance. Connection rates, even where mandated by law, tivity in the tropics, where rapid cycling of material
have been very low. Of the eight sewer systems included through the biosphere is a major element in the efficien-
in this study, three were operating close to capacity. cies of waste treatment ponds.
One of those was in a Japanese city, and the other two Distributions of most of the diseases shown in maps
were African systems built in the 1950s. Nevertheless, 12 through 19 indicate the environmental influence on
many cities have a central commercial area with high- health in the tropics. The limits are based on reported
rise buildings in which sewerage may be the most cases, and the absence of cases may be because of the
feasible solution. The lesson seems to be that the absence of the disease itself or of specialists who can
economies of scale in sewerage are illusory in areas recognize it.6
where consumer acceptance is not assured. In develop- In contrast to the regional or global environmental
ing a sanitation package for a city, planners should influences, local changes in land use are often the
(Text continues on page 39.)
MAP I Average January Temperature
(degrees Farenheit)
,ouree< -A. Natio.a ,k c and Jtterc Administratn IN oalder. C' .. )3 :o " . r o
.Source: U.S. Nationael O)ccanic and Atmospheric Administration (im)^QA) I BOUI&r. Celo.), fromi U S. Department of Commerce rec(ords.
2-
20
MAP 3. Generalized Annual Global Precipitation
(millimeters)
7 <250; 250-5(0; 50()},,O) m 1,000-2.000 >2,000.
Source Same as for map I.
MAP 4. Temperature and Precipitation, Central and South America
(degrees Celsius; millimeters)
25,50 940
1 _ON
700N
i X wk/ 9-4 -\7 200
50 N I1 I os
1034t 2 5200S
300N Oaaa *--30cS
2 00N Patz~~~~~cuaro 6Z
100N Mana2,1011Guat50
3 dry season; jf wet season; wet season, precipitation more than 100 millimeters.
Numbers on inset charts indicate, in order, average annual temperature (�C) and precipitation (millimeters). Horizontal scales are in months-January through December in
the northern hemisphere, July through June in the southern hemisphere-and showperiods of freezing (solid bars) and frost (hatched bars). Left-hand vertical scales ildicate
temperatures above OC in 10' intervals; right-hapd vertical scales indicate 0-100 millimeters of precipitation in 20-millimeter intervals and 100 millimeters of precipitation in
100-millimeter intervals.
Sources: Adapted from H. Walter and H. Lieth, Klimadiagram Weltatlas (Jena: VEB Gustav Fischer Verlag, 1960) and H. Walter, E. Harnickell, and D. Mueller-Dombois,
Climate-diagra;n Maps (Berlin: Springer-Verlag, 1975). - 1960 Gustav Fischer Verlag and 1975 Springer-Verlag, respectively. Used by permission.
MAP 5. Temperature and Precipitation, Asia
(degrees Celsius; millimeters)
70| N 1 1 70_N
600N~~~~~~~~~~~~1,0 06O
50N NOO
See map 4 for explanation of inset charts.Seoul '
Sources: 40o a
30'N 3O
200N 2N
1 O0N423ION
00la
1 00S~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~0
dry season; wet season; wet season, precipitation more than 100 millimeters.
See map 4 for explanation of inset charts.
Souirces: Same as for map 4.
MAP 6. Temperature and Precipitation, Africa
(degrees Celsius; millimeters)
AL28,60 791- _
30�N = ,~: 20,80 26 30�N
20�N I 20�N
10ON IO N
41 10�00 20, 60 835 00
1 00SI O
0�S k S 44_8- ..... - d1
.6 7_ .:--1: r_:: .
; 20,80 44 Frnitan /2 S
0�S~~~~~~~~~~~~~~~~~~~~1, 6 01:
300S30S
r44 I I I1 1 1
9. dry season; wet season; wet season, precipitation more than 100 millimeters.
See map 4 for explanation of inset charts.
Sources: Same as for map 4.
MAP 7. Aridity Index for Asia
70EN 70�N
600N 600N
500N 500N
400N 400N
300N 10300N
200N 200N
1 O0N 1 O0N
f humid; E savannah or steppe. El desertification; E desert.
Isopleths show ratios of potential evaporation to average precipitation. Ratios are calculated by dividing mean annual net radiation by product of mean
annual precipitation and latent heat of vaporization.
Sources: After Budyko-Lettau. Adapted from D. Henning, Atlas of Climate Aridity Indices (unpublished) and F. K. Hare, Climate and Desertification
(Toronto: University of Toronto Press, 1976). - 1976 University of Toronto Press. Used by permission.
MAP 8. Aridity Index for North and South America
SOON 1 D0N
700N ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~~~~~~~~~~~20
30ON~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~0
500N ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~~~~~~~~~~~30
200N ~~~~~~~~~~~~~~~21400S
IOON 5006
huid;i sdavannah or steppe; desertification; m desert.
See also note to map 7.
S'ource.s: Same as for map 7.
MAP 9. Aridity Index for Africa and Australia
b 0
z humid; 2 avannah or teppe; u deertificatio; S desert
200N
1 00S 1 00N
200S 00
N ,~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~:
300S 100OS
400S 50200S
005S 3005
F-humid; savannah or steppe; desertification; desert.
See also note to map 7.
Sources: Same as for map 7.
MAP 10. Potential Productivity by Annual Carbon Fixation
(grams of carbon fixed per sqiaic meter annually)
>800; [ 400-800; [ 100-400; 0 (-1(0;0 oceans 0-200; J oceans >200,
Potential productivity, a measurement of the amount of plant material produced aniually, is the response of plants (and the animals that eat them) to the combination of total annual
sunlight, temperature, and precipitation (see maps 1-3). High values indicate rapid recycling of nutrients, potentially rapid growth of living matter, high year-round efficiency of sewage
oxidation ponds, and favorable conditions for fish culture in ponds enriched with night soil or sewage. Low values indicate environmental constraints uponl these processes.
Source: Adapted from 11. 1Lieth, "Modeling the Prilimary ProduCtivity of the World," in H. Lieth and R. H. Whittaker (eds.), Primary Productivity of the Biosphere (Berlin: Springer-
Verlag, 1975). i 1975 Springer-Verlag. Used by permission.
MAP 11. Generalized Distribution of Soil Types and Processes
~~X23o~2
ANTARCTIC CIRCLE
\ _ > t .7 - - - ~
laterization; X salinization; Q calcification; a gleization; E3 podzolization.
Both plants and soils are affected by climate, and regional variations occur not only in plant productivity (map 10) but also in soils and the processes governing their formation. Laterites
are clayey soils with high contents of (red) iron oxide and aluminum oxide whose nutrients have been largely leached away by rains. Saline soils are created when evaporation from soil
or plant surfaces exceeds water supply, causing dissolved salts to accumulate in the soil. Caliche is a layer, often discontinuous, of calcium and magnesium carbonates at about the
depth to which water percolates. Gley is a blue- or olive-gray layer of clay under the surface of certain water-logged soils in cold climates. Podzols are leached, acidic soils formed in
temperate-to-cold, moist climates under coniferous or mixed forest or heath. Combinations of soil types and potential productivity constitute constraints within which waste reclamation
activities can function.
Source: NOAA, Environmental Research Laboratories (Boulder, Colo.).
MAP 12. Global Spread of Cholera, Pandemic El Tor Variety from Celebes to Africa, 1961 to 1975
Source: Adapted from Richard G. Feachem and others, Sanitation and Disease: Health Atspects of Excreta and Wastewater Management, World Bank
Studies in Water Supply and Sanitation, no. 3 (Baltimore: Johns Hopkins University Press, forthcoming).
MAP 13. Known Geographical Distribution of Schistosoma haematobium and S. japonicum
S. haematobium - Africa
S. japonicum - Southeast Asia
Source: Same as for map 12.
MAP 14. Known Geographical Distribution of Schistosoma mansoni
Source: Same as for map 12.
MAP 15. Known Geographical Distribution of Ancylostoma duodenale
Source: Same as for map 12.
MAP 16. Known Geographical Distribution of Necator americanus
Source: Same as for map 12.
MAP 17. Known Geographic Distribution of Taenia saginata (Beef Tapeworm)
Source: Same as for map 12.
MAP 18. Known Geographical Distribution of Taenia solium (Pork Tapeworm)
Source: Same as for map 12.
Source. Samie as for map 12.
MAP 19. Known Geographical Distribution of Culex pipiens
E northern and southern limits of range; B Bancroftian filariasis transmitted mainly by other mosquito species, E Bancroftian filariasis transmitted mainly by C. pipiens complex;
* Residual Bancroftian filariasis transmission by C. pipiens complex.
Culex pipiens is a complex of mosquito species and subspecies. The main tropical species, and the vector of Bancroftian filariasis in thosc tropical areas
where the infection is transmitted hy Culex, is Culex quinquefasciatus (previously also known as Culex pipiens fatigans, C. p. quinquefasciatus, or C.
fatigans). Other important species are C. p. pipiens, C. p. molestus (the probable vector of Bancroftian filariasis in Egypt), and C. p. pallens.
Source: Same as for map 12.
Figure 2-2. Special Plan of Two Low-income Urban Residential Neighborhoods
X~~~ ~~~~~~~~~~~~~~~~~ L, -- :, t.: 4
0 50 100
I l I I I I I i East Asia
Scale in meters
IO) 100
l 1 l l l 1 West Africa
Scale ini meters
Source: The World Bank.
TECHNICAL AND ENVIRONMENTAL ASSESSMENT 39
limiting factor, especially in urban areas. The crowding Housing density
in single-story residential areas of two cities, East Asian In densely populated urban areas, VIP latrines,
and West African, where average population densities PF toilely and urbanks VIP s ays may
of 1,000 to 1,500 persons per hectare (10000 to ROECs, PFtoilets, and septic tanks with soakaways may
15o,000 per square kilometer) are found, is shownt be infeasible. Conventional sewerage is feasible if
figure 2-2. space kisovauabl and mosofi is ' ou pie gradients are steep enough to provide self-cleansing
byihouses2. Whaen istreetsble and highwyst are btis prin, velocities. Sewered PF systems are also feasible and can
by houses. When streets and highways are brought in, beudfofltrgains.Vcm-ukcrae
buildings suffer by being moved or truncated. The be used for flatter gradients. Vacuum-truck cartage
buildings suffer.by being moved or truncated. The from vaults is a third possibility in dense areas. The
addition of rental rooms to what was previously rela- choice among these possibilities is made essentially on
tively spacious housing is shown in figure 2-3. The economic grounds, although sullage disposal facilities
smaller of the two houses is occupied by 61 people, each and access for service vehicles are important for vault
of whom has an average of about 5 square meters of toilets.
living space (from figure 2-3) and no more than 9 It is not easy to define at which population density
square meters of total space (equivalent to about 1, 100 on-site systems (such as vip latrines, ROECs, PF, and
persons per hectare). Even under these conditions, DVC toilets) become infeasible. The figure is probably
there is room for extended household latrines using most commonly around 250-300 persons per hectare
buckets or vaults. By way of comparison, sewered for single-story homes and up to double that for two-
communal latrines would occupy up to 3 percent of story houses. Pit latrines, however, have been found to
total land area where population densities are about . . ' '
1,000 persons per hectare and up to 10 percent if shower provide satisfactory service at much higher population
',000 persons per hectare and up to IO percent if shower densities. The essential point is to determine, in any
and laundry facilities are provided (not including space
for clothesyfaclinies) are provided (not including space given situation, whether or not there is space on the plot
to provide two alternating pit sites that have a mini-
smum lifetime of two years, or whether the pit could be
Levels of water supply service easily emptied if space for alternating pit sites is not
Hand-carried supplies from a public water hydrant available. For off-site systems (such as vaults and
restrict feasible technologies to those not requiring wa- cartage), the limiting factor is normally the accessibil-
ter, such as VIP latrines, ROECs, and DVC toilets. PF ity of the vault, not population density-so that, in very
toilets may be feasible in a sociocultural environment crowded and irregularly laid-out areas, bucket latrines
where anal cleansing practices already require the car- and communal facilities may be the only options.
rying of water to the toilet. Even then, however, a
sufficient amount of water may not be available for
flushing. A system that requires water to transport Complementary investments
excreta is clearly not feasible. The facilities mentioned Off-site night-soil or sewage treatment works are
above can be converted to water-seal units, if desired, required for vault toilets, sewered PF toilets, and con-
when the water supply service is improved by a yard or ventional sewerage systems. Sullage disposal facilities
house connection. must be considered for all household systems and vault,
Yard connections permit PF and vault toilets, but bucket, and community facilities. For those systems,
not cistern-flush toilets. If sullage generation exceeds achieving disposal through reclamation (the reuse po-
50 liters per capita daily, sewered PF toilets also be- tential) must be thoroughly and realistically examined,
come technically feasible. The choice among these ad- especially in areas where excreta reuse is not a tradi-
ditional possibilities and vip latrines, ROECs, and DVC tional practice. For example, DVC latrines may be
toilets, which are also still technically feasible, de- provided where there is a demand for reuse. Other
pends on other factors such as soil conditions, housing technologies that require off-site treatment facilities
density, and consumer preferences. have high potential for sludge or night-soil reuse.
Household connections make cistern-flush toilets
with conventional sewerage or septic tanks and soak- Potential construction by homeowners
aways technically feasible. Sewered PF toilets are also for
possible; but they have high capital costs, and alterna- Where financial constraints are severe, the potential
tive improvements in sullage disposal may be economi- for "self-help" construction of the various technologies
cally more attractive. Sanitation technologies are very should be considered. Self-help can provide the un-
sensitive to water use. Figure 2-4 illustrates schemati- skilled labor and some (but not all) of the skilled labor
cally how various levels of water use lead to different required for the installation of vip latrines, ROECs, and
sanitation options. DVC and PF toilets. It requires organization and super-
Figure 2-3. Typical Floor Plan of Low-income Rental Units
I--- - - - - - BR12BRI3 -BR 13 F
BR 12) (O + 5) Future (22) (3+ 2) (2+1) (6+
Future extension Bath
extension _
�I_ _ _ _ _ _ BR I
i6 t 5! / -~~~~~~~~~~~---2 ~~~~(I t 0} / BR 4 RI
BR 11 2 BR 12
(6 + 5) (1(+3)
Tree BR 11 R 4 0
BR 10
(0 + 2
Washing and drying of clothing, BR 6 BR IO
family gathering, eating, B I+0 4+0
storage of household effects, (2 + 0)
BR 9 playgrounds for children
(I + 0)Kihe
I BR 8 2
(family BR6 BR 5 BR4
ivorkshop BR7 (2 +0) (2 + 2) (0 � 3)/
room) (2+ 1)
0~~ to
Scale in meters Construction sequence
Served by standpipe: BR bedroom.
Note: Numbers in parentheses indicate numbers of adults and children in each bedroom.
Source: The World Bank.
Figure 2-4. Schematic of Relations between Levels of Water Service and Options for Sanitation
Combincd with municipal scwagc (Japan)
Fcrtiliter
Carrv 5-2D Icd Raw
1TraditionalAnmlod
Vendor 5-20) lcdAnmlfo
= == On-site Agriculture
Animal loud
Agruculturc
Fcrtilizcr
1-2 lcd excrctra Ltlid surfac Raw r
Carry 5 -20 lcd dAnimal foiod
Standpipc | Man lal 5 2(1 Icd Manu.d Agriculturc
Vendor Horse-drawn 5-40 le(i f ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~l till,f'ril'c
Animal fooid
CarrySltC -itE Agriculture
Neighborhood Carry t I tildle i
amenities Latrine R.lw_
Shower/la mndry -; Aminal food
_ _ Mcchalnical - Agriculture
C(Mpobt!2-- Animal food
_ Agriculture
44 ~~~~~~~~~~~~~~~~~~~~~~~~~~~<4(1 lcd Pit pirivis/horc-holc latrincs .
'_ _ Soi, I Groundwater
Compo t ig toilets Solids Groundwater
Supply Solids
Biogas unit Methanc Energy
Combincd LLq d L
Yard spigot 3(t801 lcd Garbage Laid-surlace Groiundwater
burial
Cesspoolfscptic tank (with ncxretal
Stock or gardpn waterig
CcslpoLe/srppic Ian'is Sdads Groundily
5 40 Icd Ra lw ewilge Llndt dispos.;l
Surfacc at{Cl
Municipal sewer system Etflucnt | tIttundE tr rch.rg
I rc lted cwagc Dlgest(onI C|ondae rehrgergjc
I~ Sludgeewag
Full phtmhtng >8(t Icd ~~~~~~~~~~~~~~~~~~~~~~~~Solids1-
Full pitimbing >80 lcd~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Lalnd di,po,.d
Icd Liters per capita dailv.
42 ANALYSIS OF FIELD STUDY RESULTS
vision by the local authority, especially in urban areas. therefore, is to exclude certain technologies in a given
The other technologies have less potential for self-help situation, rather than to select the best. The choice
labor and, indeed, require experienced engineers and among the remaining technologies is often based princi-
skilled builders for their design and construction. pally on considerations of cost, user preferences, and
reliability. Algorithms to aid in the choice of technol-
Hygienic habits of users ogy are described in chapter 9.
The choice of anal cleansing materials, in particular,
can affect the choice of technology. PF and cistern-flush Treatment Alternatives
toilets cannot easily dispose of some anal cleansing
materials (for example, mud balls, corncobs, stones, or The objectives of night-soil or sewage treatment are
cement-bag paper) where a traditional practice of to eliminate pathogens so that human health will be
disposing of such anal cleansing materials outside the protected and to oxidize organic matter so that odors,
toilet does not exist. The practice of using water for anal nuisance, and environmental problems (such as algal
cleansing may present problems for pit latrines in soil blooms or fish kills) will be eliminated. The first
with limited permeability or for DVC toilets, the con- objective may be achieved by the separation of feces
tents of which may become too wet for efficient com- from the community and the second by various combi-
posting. nations of separation, sedimentation, digestion, and
oxidation.
Institutional constraints Details of conventional sewage treatment process-
es-designed primarily to oxidize organic matter- are
Institutional constraints often prevent the satisfac- dsrbdi tnadsntr niern et.
tory operation of sanitation technologies even when the
technologies are properly designed because adequate review here of the objectives and principles of the health
maintenance (at the user or municipal levels or both) aspects of sewage treatment as they apply to developing
often cannot be provided. Thus, educational programs countries, together with some principles of design of
foftsens candinotibeuprovided.vThu,meducationalgpr ra selected technologies particularly suited to the treat-
for users and institutional development should gener- g~
ally form an integral part of program planning for ment of night soil and sewage in developing countries, is
sanitation. Changes, especially those in social attitudes, pprP
can be accomplished only slowly and may require a
planned series of incremental improvements over time. Conventional treatment processes
The conventional treatment observed in developing
countries during this research had the technical disad-
Comparison of Technology vantages of extremely poor pathogen removal and
frequent operation and maintenance problems from
From the foregoing discussion of the factors affect- shortages of properly skilled personnel and imported
ing the selection of technology, the technical suitability spare parts.
of various technologies for application in a specific Effluent from a trickling filter plant with about five
community can be determined. As a first step, compar- hours of retention will contain significant concentra-
ative criteria must be defined. One possibility is to tions of viruses, bacteria, and protozoa and helminth
compare the technologies in a matrix that displays ova and is thus unsuitable for unlimited reuse in
performance according to the established criteria. Such agriculture. Activated sludge plant effluent with, say,
a matrix, which can serve as a guide for nontechnical twelve hours of retention, is better than that from
readers and a convenient summary for professionals, is trickling filters but will still be microbiologically con-
given in table 2-3. Ranking technologies by means of taminated.
subjective weighting produces a numerical comparison Batch digestion of sludge for 13 days at 50'C in a
of spurious precision. Moreover, in any given commu- heated digester will remove pathogens and reduce
nity there are always basic physical and cultural attri- volatile solids by some 50 percent. Digestion at 30 'C
butes that-in conjunction with the existing level of for 28 days will remove protozoa and most entero-
water supply service and the community's general viruses. Digestion for 120 days at ambient tempera-
socioeconomic status-limit the choice of technologies tures will remove all pathogens except helminths.
considerably, irrespective of the overall scores achieved Sludge drying for at least three months will be very
in a comparison by numerical matrix of all possible effective against all pathogens except helminth ova (see
technologies. The most useful function of a matrix, chapter 4).
TECHNICAL AND ENVIRONMENTAL ASSESSMENT 43
Other methods of sewage treatment that are used in create shaded breeding sites. This can be prevented by
industrial countries include oxidation ditches, aerated providing pond depths of at least I meter and concrete
lagoons, sand filtration, chlorination, and land treat- slabs or stone riprap at the upper water level.
ment; these are described in a number of standard
works.' Aerobic composting
Waste stabilization ponds Rapid stabilization and pathogen destruction is
ensured by aerobic composting, in which raw night soil
Waste stabilization ponds are large, shallow ponds in or sludge is mixed with straw or some other organic
which organic wastes are decomposed by a combination matter or with previously composted night soil (or a
of bacteria and algae. The waste fed into a stabilization combination of these) so as to provide a water content of
pond system can be raw sewage, effluent from sewered 40-60 percent, a carbon to nitrogen ratio of 20-30: 1,
PF toilets or aquaprivies, or diluted night soil. and bulk or workability of the mixture. This technology
Waste stabilization ponds are an economical method has been applied in the United States (notably, at the
of sewage treatment wherever land is available. Their U.S. Department of Agriculture's Beltsville Agricul-
principal technical advantage in developing countries is tural Research Center [BARC], Beltsville, Maryland)
that they remove excreted pathogens with much less to raw and digested sludge and to night soil. The least
required maintenance than any other form of treat- expensive scheme is to form windrows of the night-soil
ment. A pond system can be designed to ensure, with a mixture over loops of perforated irrigation drainage
high degree of confidence, the elimination of all ex- pipe laid on the ground. Air is then drawn intermit-
creted pathogens. This is normally not done in practice tently through the pile into the pipe by a '/3-horsepower
because the additional benefits resulting from achiev- blower and expelled as exhaust through a small pile of
ing zero survival, rather than very low survival, are less finished compost to reduce odors. Equipment require-
than the associated incremental costs. There are three ments are limited to front-end loaders and blowers;
types of ponds in common use: screens may be added if the bulking materials are to be
separated and recycled. Temperatures in the pile are
A high enough (even in winter) for a sufficient time to
particularly for strong wastes-retention times are ensure complete pathogen destruction. The operation is
one to five days and depths are 2-4 meters.
* Facultative ponds, in which oxygen for further siPleadrlal (figur 2-).
'Facultativ ponds, in which oxygn fOther schemes for sludge or night-soil treatment
biooxidation of the organic material is supplied include incineration, wet oxidation, and pyrolysis; they
principally by photosynthetic algae-they have
retention times of five to thirty days (sometimes are too expensive to be considered for general applica-
more) and depths of 1-1.5 meters.
* Maturation ponds for final settling and pathogen
removal that receive facultative pond effluent and
are responsible for the quality of the final efflu- Sullage Disposal
ent-they have retention times of five to ten days
and depths of 1-1.5 meters. The adoption of any of the sanitation technologies,
Minimum designs incorporate a facultative pond and with the exception of septic tanks and conventional
two or more maturation ponds; for strong wastes sewerage, requires that separate facilities be considered
(BOD'-biochemical oxygen demand by the standard for sullage disposal. Sullage is defined as all domestic
test-of >400 milligrams per liter), the use of anaero- wastewater other than toilet wastes; it includes laundry
bic ponds as pretreatment units ahead of facultative and kitchen wastes as well as bathwater. It contains
ponds will minimize the land requirements of the pond some excreted pathogens but, of course, considerably
system. Well-designed pond systems in warm cli- fewer than toilet wastes. It also contains many organic
mates-incorporating five ponds in series and having a compounds and approximately 40-60 percent of the
minimum overall retention time of thirty days-pro- total household production of waste organics-that is,
duce an effluent that will be essentially pathogen free some 20-30 grams of BOD per capita daily. This figure,
and suitable for unlimited irrigation reuse. however, depends on water consumption. A family with
Snail and mosquito breeding in stabilization ponds abundant water for personal and clothes washing and
will occur only if poor maintenance allows vegetation to many water-using appliances will generate more sul-
emerge from the pond bottom or to grow down the lage BOD than one that uses only small quantities of
embankment into the pond, since these conditions water for drinking and cooking.
44 ANALYSIS OF FIELD STUDY RESULTS
Table 2-3. Descriptive Comparison of Sanitation Technologies
Sanitation Rural Urban Construction Operating Ease of Self-help
technology application application cost cost construction potential
vIps and ROECS Suitable Suitable in L/M-den- L L Very easy except in H
sity areas. wet or rocky
ground
PF toilets Suitable Suitable in L/M-den- L L Easy H
sity areas
DVC (double vault com- Suitable Suitable in L/M-den- M L Very easy except in H
posting) toilets sity areas wet or rocky
ground
Self-topping aquaprivy Suitable Suitable in L/M-den- M L Requires some H
sity areas skilled labor
Septic tank Suitable for rural Suitable in L/M-den- H H Requires some L
institutions sity areas skilled labor
Three-stage septic tanks Suitable Suitable in L/M-den- M L Requires some H
sity areas skilled labor
Vault toilets and cartage Not suitable Suitable M H Requires some H
skilled labor (for vault con-
struction)
Sewered PF toilets, sep- Not suitable Suitable H M Requires skilled en- L
tic tanks, aquaprivies gineer/builder
Sewerage Not suitable Suitable H H Requires skilled en- L
gineerlbuilder
Note: L, low; M, medium; H, high; VH, very high.
a. On- or off-site sullage disposal facilities are required for nonsewered technologies with water service levels in excess of 50 to 100 lcd,
depending on population density.
b. If groundwater is less than 1 meter below the surface, a plinth can be built.
In developing countries sullage is a wastewater with provide attractive sites for mosquito breeding. Disposal
approximately the same organic pollution potential as in covered drains or sewers is subject to the same exca-
raw sewage in North America. Although its environ- vation and environmental problems as conventional
mental impact may be moderate (see the Kyoto case sewerage.
study, below), its health hazard will be many orders of
magnitude less than that of sewage (see chapter 4). Resource Recovery
Thus, an important factor to consider when choosing
sullage disposal facilities is how much the community is Technologies for resource recovery in areas included
willing to spend on environmental protection. within the present research provide for irrigation with
There are basically four kinds of sullage disposal treatment plant effluent; garden watering with sullage;
systems: casual tipping in the yard or garden, on-site crop fertilization by raw, digested, or anaerobically
disposal in seepage pits, disposal in open drains (usually composted night soil or sludge; fish culture with raw
stormwater drains), and disposal in covered drains or night soil; and methane production from municipal
sewers. The first will be adequate where water use is sludge or night-soil digesters and from household bio-
low and the soil and climatic conditions are such that gas units.
the yard remains dry and puddles of water do not form. Readily available data on health aspects were
Seepage pits can handle more water but also require collected, but were not sufficiently detailed to show
appropriate soil conditions. If stormwater drains are either presence or absence of detrimental effects from
used for sullage disposal, they should be designed with a the various resource-recovery practices. Technologies
deep (rather than flat) center section so that the small characteristic of these and similar practices are pre-
volumes of dry weather flow and sullage will not pond. sented in Appropriate Sanitation Alternatives: A
In addition, drains must be carefully maintained to be Planning and Design Manual; their general features
free of debris that could block the flow and thereby are summarized below.
TECHNICAL AND ENVIRONMENTAL ASSESSMENT 45
Water Required soil Complementary off-site Reuse Health Institutional
requirement conditions investment potential benefits requirements
None Stable permeable soil; None L Good L
groundwater at least 1
meter below surface'
Water near toilet Stable permeable soil; None L Very good L
groundwater at least 1
meter below surface'
None None (can be built above None H Good L
ground)
Water near toilet Permeable soil; groundwater Treatment facilities for M Very good L
at least 1 meter below sludge
surfaceb
Water piped to Permeable soil: groundwater Off-site treatment facilities M Very good L
house and toilet at least 1 meter below for sludge
surface'
Water near toilet Permeable soiL groundwater Treatment facilities for M Very good L
at least 1 meter below sludge
surfaceb
Water near toilet None (can be built above Treatment facilities for H Very good VH
ground) night soil
Water piped to None Sewers and treatment H Very good H
house and toilet facilities
Water piped to None Sewers and treatment H Very good H
house and toilet facilities
Agricultural reuse there are hazards of passive carriage of a range of
Agricultural reuse is the most common form of pathogens and, in some parts of the world, of Clonor-
excreta reuse. There are, however, health risks to chis sinensis (Chinese liver fluke) transmission as well.
people and animals working in the fields where excreta Control measures include enriching ponds only with
are reused and to those who consume the crops raised in settled sewage or stored night soil or sludge; placing the
excreta-enriched soil. There are also problems associ- fish in clean water for several weeks prior to harvesting;
ated with the chemical quality of the compost, sludge, clearing vegetation from pond banks to discourage the
or sewage effluent-including concentration in crops of snail host of Clonorchis; promoting food hygiene in the
heavy metals and potential damage to the soil structure handlmig and processing of fish; and discouraging the
fro hig soiu cnetais. consumption of raw or undercooked fish.
from high sodium concentrations.
Pigs are fed raw excreta in a number of South and Yields of carp in fertilized ponds vary from 200
Southeast Asian, Central American, and West African kilograms per hectare yearly in rural, subsistence ponds
locations. They provide direct and efficient conversion to 1,000 kilograms per hectare or more yearly in com-
of wastes to protein, but the health risks are obvious, mercial ponds; yields of tilapia are 2,0003,000 kilo-
and reliable epidemiological data are lacking. Thor- grams per hectare yearly in well-maintained ponds.
ogcokngx re- s e is an Fish yields can be doubled by raising ducks, whose feces
essential measure of effective pathogen control, provide additional nutrients, on the ponds. Ecological
niches in the pond can be introduced; for example, the
common carp (Cyprinus carpio) and the grass carp
(Ctenopharyngodon idella) feed primarily on benthic
Human excreta can be used for raising aquatic plants zooplankton and aquatic weeds, respectively. Up to
and animals. The four main kinds of aquaculture are 7,000 kilograms per hectare yearly can be achieved if
freshwater fish farming; marine culture of fish, shell- supplemental feeding with grass, other vegetation, rice
fish or shrimp; production of algae; and the emergent bran, groundnut cake, or the like is provided and bot-
production of aquatic plants. tom-feeding fish are added to the pond.
Reliable data on freshwater fish farming are avail- The design of fishponds is essentially the same as that
able from South and Southeast Asia. In this practice of waste stabilization ponds. Depths are usually > 1
46 ANALYSIS OF FIELD STUDY RESULTS
Figure 2-5. Schematic of Beltsville Agricultural Research Center (BARC) System
for High-rate Thermophilic Composting
(meters)
Aeration pipe is perlorated
for even air distribution b
E I',.--- V==
a a
o ii~~~ - - -- - -- - -- - - -
As needed
Plan
2,500 to 3,50
3.000 V 1/2 WHeight-i
2- + -~ Finished compost bed 7,500
Section a-a Section b-b
Note: BARC (Beltsville. Maryland) is a facility of the U. S. Department of Agriculture.
meter to prevent vegetation from emerging from the island of Taiwan, was completely self-sufficient in
pond bottom; deep ponds (>2 meters) are disadvanta- cooking fuel with the added wastes from two pigs.
geous because there is little oxygen, and hence few fish, Biogas may also be used for lighting, and large farms
in the lower layers. What matters is the correct rate of and institutions are also suitable sites for biogas units.
supply of nutrients; regular batch feeding on an empiri-
cally determined basis is recommended.
Example of Management Schemes
Biogas production for Sewage and Night Soil
Institutional and household biogas plants are opera-
tive in China, India, Korea, the island of Taiwan, and An excellent comparison of well-designed, well-man-
elsewhere and use diluted animal feces with or without aged systems for excreta and sullage disposal can be
human excreta and with or without vegetable refuse. found in Kyoto, Japan, a city of 1.4 million. Here,
The effluent slurry from these plants can be used in public health and aesthetic requirements are met by
agriculture and fishponds. The dung from one cow or conventional sewerage for about 40 percent of the
similar animal can produce around 500 liters of gas per population and by a vault and vacuum-truck system for
day; it contains 50-70 percent methane and its calorific another 40 percent. Sullage from the latter is dis-
value is around 4-5 kilocalories per liter. In contrast, charged to surface drainage facilities. After collection,
human excreta yields only 30 liters of gas per person the 1.2 liters per capita daily of night soil undergo grit
daily. The process is very sensitive to temperature, and removal, comminution, screening, and storage and are
gas production is negligible below 15'C. released into sewers at off-peak hours for subsequent
One family in Korea reported sufficient gas produc- activated sludge treatment and incineration. Trucks
tion for cooking purposes for nine months of the year are thoroughly cleaned at the night-soil transfer station
from human and household wastes. Another, on the after each trip.
TECHNICAL AND ENVIRONMENTAL ASSESSMENT 47
The areas and water quality of streams in portions of pumps
the city served by the two systems are shown in map 20. * Development of training materials, workshops, and
Diffused discharges of sullage from unsewered areas do seminars for disseminating information on low-
not affect concentrations of BOD and suspended solids cost water supply and sanitation systems and for
in the streams; increases in these constituents cannot be training professionals and technicians in imple-
distinguished from those due to urban runoff in sewered mentation
areas. Moderate increases in stream BOD and solids * Development of a methodology to determine the
downstream from the sewage treatment plants reflect most cost-effective mix of sewerage and low-cost
both the excellent removals obtained by treatment and sanitation in urban areas
the impact of point discharges to the streams. Health * Multidisciplinary evalution and pilot testing of
data from the two areas reveal no differences. Costs of methods to convert waste materials into usable
the two systems are presented in the following chapter. products.
The most significant findings from this case study Much work has been done in this last area, but
are that the less expensive vault and vacuum-truck usually only with a narrow (single-purpose) orienta-
system can provide health protection equal to, and tion. A multidisciplinary approach-studying many
protection of water quality in streams better than, that disposal and reuse possibilities and optimizing various
of conventional sewerage. Both systems are providing simultaneous outputs-will result in more efficient and
reliable service to areas of an historic, beautiful, and cost-effective solutions.
modern city.
Future Research Needs Conclusion
Most of the technologies discussed in this chapter The review of existing technologies shows clearly
have been applied successfully at specific sites and, in that low-cost sanitation methods exist that are either
the case of on-site systems, on an individual basis. It is acceptable as now used (for example, PF and vault
therefore necessary to design, implement, and monitor latrines) or capable of easy improvement (VIP latrines).
pilot projects on a community scale to: Selection of the technique to be used depends on local
conditions such as climate, soil permeability, social
TsConfirm the replicability of technologies customs, and the like. All technologies identified pro-
* fest the transfer and adaptation of technologies for vide the health benefits commonly associated with wa-
different sociocultural environments t terborne sewerage, albeit at different standards of con-
a Evaluate the ability of communities to organize venience. In short, the choice is not between different
and operate communal systems such as the empty- levels of health and sanitary conditions but between
ing of vaults and septic tanks service levels and affordability. Fortunately, this choice
* Determine effects of sullage disposal and develop is made even easier by the fact that technologies can be
methods of sullage disposal for various population upgraded over time to achieve higher standards of ser-
densities vice that keep pace with the users' ability to pay for
* Test the large-scale application of appliances with them (see chapter 9).
low water use (for example, aerated spigots and The most important consideration for the selection of
shower heads, overhead low-volume flush tanks) sanitation technology is existing and anticipated water
and their effects on sanitation. consumption of the area studied. At low water use (say,
Research is also needed in various areas to develop less than 50 liters per capita daily), sullage can usually
technologies further, to measure their effects, or to find be disposed of on site without major problems. Above
new, more efficient techniques. Among these areas for this level, on-site disposal becomes more difficult, and,
further research are: at levels above 100 liters per capita daily, some sort of
* On- and off-site sullage treatment and disposal drainage is probably required. Again, local conditions
methods (infiltration, evaporation, anaerobic fil- such as population density and soil permeability will
tration, oxidation ponds) also be determining factors. It is clear, however, that
* Testing and monitoring of the performance of the lower the water consumption, the greater are the
handpumps for water supply in rural areas and options for on-site disposal methods. For the same rea-
development of a methodology for selection (simi- son (maximum number of options), sullage and excreta
lar to that of the algorithms for sanitation) that should be disposed of separately.
would reduce present high failure rates of hand- Selection of the technology suitable in any given case
IBRD 16280
MAP 20. 135�45' CHINA f c
Sewerage and Night-soil . i
Collection Areas in Kyoto, Japan (
Sewage Treatment Plants N. KOREA
A Night-soil Transfer Plants % * REP. OF
* Water Sampling Points K6REA
BOD Biochemical Oxygen Demand K o koo
(parts per million) Toky
ss Suspended Solids (parts per million) * a O
-35�15' [III7 - Sewerage Servke Areas */35P15 acfic Ocean
Night-soil Collection Areas )
Rivers
City Boundary
-* International Boundaries (
0 5 10
KILOMETERS; C .
ROD.1. 3 ppR 7 p
SS 6.2pp S L9ppm
isBOD 29.6 B O
% BOD 12.0 ppm SS13.6 ppm SS ppm S53 p 96mpp
:t ... .:~~- ) % A
R9Opp*pp
130D 11.6ppm SS .&9ppm Bo il
FUSHIMIP PLANTw-D32 ppmN .1ppmLANT
IlODlI.Sppm SSJ3.6ppmf / SS 33. pmN
ROD 11.8 ppm SS 27.7ppm
This map has been prepared by the
World Bank's staff exclusively for
the convenience of the readers of
the report to which it is attached.
The denominations used and the
boundaries shown on this map
do not imply, on the part of the\
World Bank and its affiliates, any
judgment on the legal status of
any territoryaor any endorseement MR 195452
or aceptanee of such boundaries. IMARCH 1982
48
TECHNICAL AND ENVIRONMENTAL ASSESSMENT 49
requires a consideration of various factors in addition to (Baltimore: Johns Hopkins University Press, forthcoming). Much of
purely technical ones. For an initial evaluation, a the technical description presented in this chapter is taken from this
matrix comprising the various characteristics of companion work.
available technologies is sometimes helpful. For final 2. As is discussed in chapter 4, a well-designed and -maintained pit
tccio,hnologies, ise slometimes helpful.d For finalte latrine can provide the same level of health benefits in low-density
selection, however, the algorithms described in chapter areas as a properly maintained sewerage system can in the inner city.
9 should be used. Both the matrix and algorithms 3. Latrines have been used satisfactorily at twice this suggested
emphasize the need to take a comprehensive look at the density in areas where soil conditions or climatic factors are
proposed solution-that is, the sociocultural aspects as especially favorable.
well as the technical, financial, and economic consider- 4. Sullage is wastewater that does not contain excreta-for
ations-to avoid the installation of a system that will example, laundry water and bathwater.
not be used or will be quickly abandoned by the 5. Japanese experience has been that there is a lag time of five to
community. ten years between commissioning of a sewerage system and voluntary
connection to it by a significant number of households.
6. For further detail, see chapter 4 and Richard G. Feachem and
others, Sanitation and Disease: Health Aspects of Exereta and
Wastewater Management, World Bank Studies in Water Supply and
Notes to Chapter 2 Sanitation, no. 3 (Baltimore: Johns Hopkins University Press,
forthcoming), a companion to this study.
7. For example, Gordon M. Fair, John C. Geyer, and Daniel A.
I. For engineering designs and detailed technical information on Okun, Water Purification and Wastewater Treatment and Disposal
each technology, see also John M. Kalbermatten and others, (New York: John Wiley and Sons, 1968).
Appropriate Sanitation Alternatives: A Planning and Design 8. Ibid. See also D. Duncan Mara, Sewage Treatment in Hot
Manual, World Bank Studies in Water Supply and Sanitation, no. 2 Climates (New York: John Wiley and Sons, 1976).
3
The Economic Comparison
COMPARATIVE COSTING lies at the heart of the analy- cost figures.
sis of alternative sanitation technologies. The definition A scoring device that has been used on occasion for
of technological "appropriateness" developed in chap- ranking alternatives with unquantifiable benefits is a
ter I is based partly upon a systematic ranking of matrix that lists both cost and benefit components and
feasible alternatives according to their economic costs. assigns values (or relative ranks) to each alternative
Implicit in this definition is the search for a common based on an arbitrary scale (or the total number of
denominator for the objective comparison of diverse alternatives). Varying degrees of complexity can be
systems. That common denominator should reflect built into matrix ranking by weighting the criteria or by
both the positive and negative consequences of a given using complex, summary variables of the values. Re-
technology and also indicate its overall "score"-either gardless of the variations, however, the lack of objectiv-
on an objective scale or relative to other alternatives. ity in the procedure remains a major disadvantage. It is
One scoring measurement commonly used in project unlikely that two equally competent analysts would
evaluation is the benefit-cost ratio.' It has the advan- arrive at the same value for various alternatives or even
tage of providing a single, summary figure representing the same ranking across alternatives. There is no
the net economic effect of a given project, which can objective basis for selecting one summary measure over
then be readily compared with that of alternative another or any one set of weights for the cost and
projects. The disadvantages of benefit-cost calculations benefit categories. Such a nonreplicable method is not
are that they do not easily accommodate noneconomic only unscientific but can be misleading to the nontech-
benefits and costs (particularly if these are unquantifi- nical reader, who may mistake its statistical complexi-
able); they may give misleading results when applied to ties for objectivity.
mutually exclusive projects; and they may not reflect In general, there is no completely satisfactory scoring
macroeconomic goals such as the creation of employ- system for comparing alternatives with unquantifiable
ment or the generation of savings and investment. benefits. Only in the case of mutually exclusive alterna-
Fortunately, the last two problems can be remedied by tives with identical benefits can a cost-minimization
variations of the basic calculations.2 The difficulties of rule be applied. In such cases the alternative with the
measuring benefits for sanitation projects, however, lowest present value of cost, when discounted at the
cannot be readily overcome. Indeed, in the case of water appropriate rate of interest, should be selected. For
supply projects it has been concluded that the theoreti- given levels and qualities of service, the least-cost
cal and empirical problems involved in quantifying alternative should be preferred. But, where there are
incremental health benefits are so great as to make differences in the output or service, the least-cost
serious attempts at the measurement of benefits inap- project often will not be the economically optimal one.
propriate as part of project appraisals.3 Alternative sanitation systems provide a wide range
There are also unquantifiable costs associated with of benefit levels. Although most properly selected
alternative sanitation technologies. Although it is gen- systems can be designed to provide the potential for full
erally possible to assess qualitatively the environmental health benefits (that is, to ensure pathogen destruc-
consequences of installing a particular system, it is very tion), the convenience to users offered by an indoor
difficult to quantify them since no "market" for such toilet with sewer connection is hard to match with a pit
public goods exists. It is even more difficult to compare privy. Many benefits exist in the mind of the user, and
consequences of installation with the environmental varying qualities of service result in varying benefit
situation that would develop without the project's levels. For this reason, a least-cost comparison will not
implementation, thus to determine net benefit or net provide sufficient information to select among sanita-
50
THE ECONOMIC COMPARISON 51
tion alternatives. Nonetheless, if properly applied, it community may incur costs that could have been
will provide an objective, common denominator that postponed. By waiting too long, the community might
reflects tradeoffs in cost corresponding to different face a rise in the per capita cost of the project (in real
service standards. Once comparable cost data have terms) because of increases in population density, for
been developed, the consumers or their community example, which could aggravate construction difficul-
representatives can make their own determination of ties for some technologies.
how much they are willing to pay to obtain various Once the relevant costs to be included have been
standards of service. identified, the second costing principle concerns the
Thus, the economic evaluation of alternative sanita- prices that should be used to value those costs. Since the
tion technologies comprises three components: compa- objective of economic costing is to develop figures
rable economic costing, the maximizing of health ben- reflecting the cost to a particular country of producing
efits from each alternative through proper design, and a good or service, the economist is concerned that unit
the involvement of users in making the final cost- prices represent the actual resource endowment of that
benefit determination. This chapter deals with the first country. Thus, a country with abundant labor will have
of these. Chapter 4 discusses the public health aspects relatively inexpensive labor costs because labor's alter-
of sanitation alternatives, and chapter 5 develops native production possibilities are limited. Similarly, a
methods of promoting the involvement of users in country with scarce water resources will have expensive
choosing technology. water costs, in the economic sense, regardless of the
regulated price charged to the consumer. Only by using
prices that reflect actual resource scarcities can the
Economic Costing in Theory economist ensure that the least-cost solution will make
the best use of a country's resources.
The primary intent of economic costing is to develop Because governments often have diverse goals that
a price tag for a good or service that represents the may be only indirectly related to economic objectives,
opportunity cost to the national economy of producing some market prices may bear little relation to real
that good or service. Translated into practice, this economic costs. For this reason it is often necessary to
intent can be summarized in three principles to be "shadow price" observed, or market, prices to arrive at
followed in preparing cost estimates. meaningful costs for components of a sanitation tech-
The first principle is that all costs to the economy, nology. Calculating these shadow rates, or conversion
regardless of who incurs them, should be included. In factors, is a difficult task and requires intimate knowl-
comparing costs of public goods such as water or edge of an economy's workings.4 The shadow rates used
sanitation, too often only costs that the public utility in this report were obtained from World Bank econo-
pays are considered in a cost comparison. The costs mists specializing in the countries concerned.
borne by the household are often ignored. In analyzing One of the most important shadow values is the
the financial implications of alternative technologies, opportunity cost of capital. This is defined as the
such a comparison would be appropriate. For an eco- marginal productivity of additional investment in the
nomic comparison (that is, for the determination of the best alternative use. It can also be thought of as the
least-cost solution), however, it is necessary to include price (or yield) of capital. In countries where capital is
all costs attributable to a given alternative-whether abundant, such as the industrialized countries of
borne by the household, the utility, the national govern- Europe, one expects the yield on capital to be relatively
ment, or other entities. low. This is because capital has already been employed
The determination of which costs to include should in its most productive uses and is now being substituted
rest on a comparison of the situation over time, with and for labor or other inputs in less and less profitable areas.
without the project. This is not the same as a "before In many developing countries, however, capital is a
and after" comparison. Rather than using the status scarce commodity and therefore has a relatively high
quo for the "without" scenario, the analyst must esti- opportunity cost and should be used in those areas
mate how the current situation would improve or where it produces a very high return. Therefore, a least-
deteriorate over the project period were the project not cost comparison of alternatives that differ in their
to be undertaken. In the case of sanitation systems for capital intensity should reflect the real cost of capital to
urban fringe areas, for example, the costs of the economy rather than use capital's market price.5
groundwater pollution and the difficulty in siting new The third principle of economic costing is that
latrines are likely to increase over time as population incremental rather than average historical costs should
pressure mounts. There is likely to be an optimal time to be used. This principle rests upon the idea that sunk
undertake a sanitation project. By acting too soon the costs (those already incurred) should be disregarded in
52 ANALYSIS OF FIELD STUDY RESULTS
making decisions about future investments. Analysis of one used by ten people. For this reason, all costs
the real resource cost of a given technology must value presented in this chapter are given in household as well
the components of that technology at their actual as per capita units.
replacement cost rather than at their historical price. In A further difficulty is that the per capita construc-
the case of sanitation systems, this is particularly tion cost of a sewerage system will vary considerably as
important in the evaluation of water costs. Because the design population varies. In addition, it would be
cities develop their least expensive sources of water misleading to use the design population in deriving per
first, it generally becomes more and more costly (even capita sewerage costs to compare with those of a pit
excluding the effect of inflation) to produce and deliver latrine. In the case of sewerage, the benefits only reach
an additional liter of water as the city's demand grows. a portion of the users during the early years. The
If the analyst used the average cost of producing today's latrine's "design population," in contrast, is served
water, the evaluation would seriously underestimate immediately upon completion of the facility. Any
the cost of obtaining water in the future. The decision to technology that exhibits economies of scale will result
install a water-carried sewerage system will increase in a diversion of the cost and benefit streams. With such
the newly served population's water consumption by a facility, the investment costs are incurred at the
around 50 to 70 percent.6 Thus, in calculating the costs beginning of its lifetime and the benefits (services) are
of such an alternative, it is extremely important to value realized gradually over time. A schematic representa-
properly the cost of the additional water required. tion of this diversion between cost and benefit streams is
provided in figure 3-1. The construction period lasts
until T,, when the new facility is commissioned and
Special Problems of Sanitation Projects begins to produce benefits. As demand grows over time,
more and more of the plant's capacity is utilized until,
The application of these costing principles to sanita- at T2, the facility is fully used and provides full benefits
tion projects is difficult for several reasons. The chief (that is, serves its design population).
difficulty is the problem of finding a scaling variable Just as costs incurred in the future have a lower
that allows comparison among diverse technologies present value than those incurred today, benefits re-
that are designed to serve different numbers of people. ceived in the future are less valuable than those received
On-site systems, such as pit latrines, are generally immediately. In the case of the derivation of per capita
designed for a single family or household. The latrine's costs, this means that serving a person five years hence
overall lifetime will depend on how many people use it. is not worth as much as serving the same person now. To
The life of some components (such as a vent pipe), divide the cost of a sewerage system by its design
however, may be independent of usage, so that the population would understate its real per capita cost
annuitized per capita construction cost of a latrine used when compared with that of a system that is fully
by six people will probably not be the same as that of utilized upon completion.
Figure 3-1. Benefit-Cost Divergence over Time
Total benefit
Total cost
I I I I II I I I I I I I I I
t, t2
Time
t, Time of sanitation facilitv's commissioning, t2 time of full use of facilitv s capacity
THE ECONOMIC COMPARISON 53
A good method that has been used to overcome the sullage wastes. In sewerage, most septic tanks, and
problem of rates of capacity utilization differing across some aquaprivy systems, sullage is disposed of along
systems is the average incremental cost (AiC) ap- with excreta. In most of the on-site technologies,
proach.7 The per capita AIC of a system is calculated by sullage disposal must be accomplished separately,
dividing the sum of the present value of construction through stormwater drains or ground seepage. If storm-
(C) and incremental operating and maintenance (0) water drains are present (or would be constructed
costs by the sum of the present value of incremental anyway), then the incremental cost of disposing of
persons served (N): sullage is very small because storm drains are usually
designed to handle flood peaks.9 If sullage is left to soak
t= T into the ground, nuisance and possible health risks may
E (C1 + Od)/(1 + r)'-1 be created (depending on climate, soil conditions, and
AIC, = = T groundwater tables).'" Alternatively, separate disposal
E N,1(1 + r)'-' of sullage may be considered a positive benefit in areas
t= 1 where the population recycles kitchen and bathwater to
irrigate gardens or dampen dust. In such cases, the
where r is the opportunity cost of capital and Tis the life removal of sullage through the introduction of a sewer-
of the facility. All costs are in constant (noninflated) age system would produce a negative benefit. In a
prices and have been appropriately shadow priced. For particular case it is not difficult for the analyst to decide
a system that is fully utilized immediately, this calcula- how to treat costs of sullage removal when comparing
tion reduces to the familiar calculation of annuitized different sanitation streams. For the purposes of this
capital and incremental operating and maintenance study, however, and because a more general compari-
costs divided by the design population. son is required, a consistent assumption has been
In practice it is often easier to calculate the AIC on applied. Therefore, the costs in tables 3-1 through 3-11
the basis of a volume measure (for example, cubic include sullage disposal only if the sanitation system
meters) rather than by person served. For the sewerage itself is designed to accommodate it. This is true of all
costs in this study from the cities of Gaborone, Khar- the sewerage systems, all the septic tanks, and the
toum, Malacca, Managua, and Ndola, the AIC per Ndola and Newbussa sewered aquaprivies.
cubic meter was calculated first because year-by-year A final problem in preparing comparable cost figures
projections of treated wastewater were available. These for sanitation systems is the method to be used in
volumetric costs were then transformed into per capita gathering data. This study is statistically based, in
and per household costs using per capita demand contrast to a synthetic framework that develops an
figures. ideal model and tests the effects of varying assump-
The AIC method is useful in deriving per capita costs tions. Both methods have their advantages and disad-
that can be meaningfully compared with those of vantages. Because so little is known about the technol-
systems with different rates of use. This is especially ogy or costs of nonconventional sanitation systems, it
important in evaluating sanitation systems because of was decided that a broadly based study involving many
the large variation in economies of scale (for example, systems in many different settings would provide the
sewerage versus on-site systems or cartage). Whereas best comprehensive frame for designing particular
economies of scale are often the engineer's best friend studies or, indeed, for selecting "typical" technologies
(in the sense that he can overdesign "to be on the safe and settings to proceed from in developing a synthetic
side" without incurring unduly large increases in cost), model. The major disadvantage of a statistical ap-
they cause institutional and financial headaches when proach, however, is that it is very difficult to identify
demand assumptions turn out to be optimistic or the the factors that cause increased or decreased costs
city grows in a different direction from the one ex- because it is impossible to vary one factor at a time
pected. Because of the inflexibility of large-scale sani- while holding all others constant. Cross-country com-
tation systems once they are built, their financial parisons can be misleading unless one is familiar with
feasibility, and even technical success, is extremely the background of the cases compared. For this reason,
sensitive to the assumptions used in the design analysis. most technological comparisons are made within a
In communities where there is no demand history on single country-whenever possible, within the same
which to base forecasts, it is extremely risky to recom- community.
mend a system with large economies of scale and with a In one case, that of Malacca, a synthetic study was
correspondingly long design period.! carried out to test with more precision the cost differen-
An additional problem in deriving comparable costs tial between sewerage and vacuum-truck cartage. In
for sanitation systems is the differing treatment of Gaborone, an excellent comparison of the costs of on-
54 ANALYSIS OF FIELD STUDY RESULTS
site systems was possible because of recent work carried average number of persons in a household.
out there under a project of the International Develop- Because both investment and recurrent costs must
ment Research Centre. It is expected that more cost- be included for a least-cost comparison, and because
modeling exercises will be undertaken as routine different technologies have different lifetimes, the
feasibility studies expand to include nonconventional TACH is an annuitized (or annual) figure. It should
sanitation systems. not, however, be interpreted as an amount of money
to be spent annually for a particular technology. To
Field Results illustrate this, consider the case of the pour-flush
(PF) toilet with a mean TACH of $18.7. This figure
The costs discussed below have been disaggregated is derived as follows:
in two ways, by function and by investment versus Cost
recurrent costs. In disaggregating by function, the (U.S. dollars)
categories used are on-site facilities, collection, treat- Mean investment cost 70.7
.' ' . Mean lifetime (years) 22.0
ment, and reuse. This distinction is made primarily Mean annuitized investment cost 13.2
because disaggregating by function allows a broad Mean annual maintenance cost 2.4
examination of the costs of repackaging components. Mean annual water cost 3.1
For example, many treatment alternatives can be TACH 18.7
linked with a variety of collection systems, on-site The figure for mean annuitized investment cost is the
facilities, or both. In addition, disaggregation by func-
tion is amenable to "value engineering" by its identifi- weighted average of three case studies with opportunity
cation of the areas in which the greatest potential for costs of capital of 12, 20, and 20 percent and lifetimes of
cost savings exists. It also provides the financial analyst twenty, twenty, and twenty-five years, respectively.
with a rough guide for determining the proportion of Although the TACH is $18.7, the actual cash expendi-
system costs that must be borne by the utility relative to ture (including water costs) is only $5.5 annually.
the costs incurred directly by the household. The latter The TACHs obtained for ten technologies (arranged
cost is a useful figure for estimating the willingness of by ascending mean TACH) are summarized in table 3-1.
the consumer to pay utility rates; this willingness will be Several summary statistics are shown because of a wide
based, in part, on the costs to the household of obtaining variation in the number of case studies and the range of
the private facilities that will enable it to make use of costs." Contrary to expectation, the technologies do not
the utility's service. divide cleanly into community and individual systems
The second type of disaggregation is the separation when ranked according to cost. The most expensive
of capital and recurrent costs. The difference between technological group (with a TACH greater than $300)
technologies with high capital cost and high recurrent includes sewerage and Japanese and Taiwanese septic
cost generally parallels that of capital-intensive versus tanks. The middle-range technologies (those with
labor-intensive technologies. This is because the invest- TACHs between $150 and $200) are aquaprivies,
ment costs of most systems are mainly in capital, and sewered aquaprivies, and Japanese cartage. The low-
recurrent costs are mainly in labor. The distinction is cost technologies (those with TACHs less than $100)
made here between investment and recurrent costs include both community systems (such as bucket
-rather than between capital and labor-partly to latrines) and most individual systems. The divisions
emphasize the main cause of the difference and partly between high-, medium-, and low-cost technologies are
to stress the important institutional implications of fairly sharp, with large buffer areas available for
managing a system with high recurrent costs. upgrading systems. The fact that variations on septic
tanks and vacuum-truck cartage appear in two
categories indicates the potential for installing a low-
cost facility at an early stage of development and
The single most useful figure for cost comparisons of improving its standard of service as development
technologies is the total annual cost per household proceeds.
(TACH), which includes both investment and recurrent Within the low-cost group of technologies there is a
costs (properly adjusted to reflect real opportunity costs fairly large variety of systems, ranging from aqua-
and averaged over time by the AIC method). The TACH privies and simple septic tanks to pit latrines and PF
would, however, be misleading when applied to commu- toilets. Vacuum-truck cartage (non-Japanese) and
nal facilities or cases where several households share bucket cartage, with TACHs in the $35 to $65 range, fall
one toilet. In those instances, an adjusted TACH has in the middle of this group. The vacuum-truck cartage
been calculated by scaling up per capita costs by the figures, however, are derived mostly from case studies
THE ECONOMIC COMPARISON 55
Table 3-1. Summary of Total Annual Cost per Household (TA CH) for Sanitation Technologies
(1978 U.S. dollars)
Observations
Technology (number) Mean Median Highest Lowest
Low cost
Pour-flush (PF) toilet 3 18.7 22.9 23.3 10.1
Pit latrine 7 28.5 26.0 56.2 7.6
Communal septic tank, 3 34.0 39.0 48.0 15.0
Vacuum-truck cartage 5 37.5 32.2 53.8 25.7
Low-cost septic tank 3 51.6 45.0 74.5 35.4
Composting toilet 3 55.0 56.2 74.6 34.3
Bucket cartage' 5 64.9 50.3 116.5 23.1
Medium cost
Sewered aquaprivya 3 159.2 161.4 191.3 124.8
Aquaprivy 2 168.0 168.0 248.2 87.7
Japanese vacuum truck cartage 4 187.7 193.4 210.4 171.8
High cost
Septic tank 4 369.2 370.0 390.3 306.0
Sewerage 8 400.3 362.1 641.3 142.2
a. Per capita costs were used and scaled up by the cross-country average of six persons per household to account for large differences
in the number of users.
in Korea and the island of Taiwan, which exhibit a groupings of technologies in high-, medium-, and low-
degree of labor efficiency that might be difficult to cost systems indicates that the groupings are probably
replicate in other parts of the world. Figures for bucket accurate, although the means may be 50 percent too
cartage are mostly from Africa and represent poorly low or too high.'3
functioning systems that probably should not be The total variation is caused in part by differences in
replicated without upgrading. Thus, the TACHs of the costs of basic inputs (such as labor) and in part by
community systems in the low-cost group are likely to differences in the combination of inputs used (for
understate their cost of construction and operation in example, labor-intensive versus capital-intensive treat-
other countries. Of course, since all of the costs ment processes). To some extent, these two factors
summarized in table 3-1 are derived from particular offset one another because a country with high capital
case studies, none can be considered an accurate costs, for example, would be expected to choose a less
representation of what it would cost to build a capital-intensive treatment process. For two of the
particular system in a different country.'2 systems, vacuum-truck cartage and septic tanks, the
difference in the combinations of inputs seems to be
very important because the case studies' costs exhibited
Cost comparison a bimodal distribution, which could be directly traced
to differences in the technologies employed in different
It is useful to consider the overall variation of cost in locations. In no two case studies is the exact design of a
different countries before making an examination of system replicated; that is, no two pit privies are exactly
the cost data for each technology. The magnitude of the alike. For most of the technologies, however, the varia-
total variation is quite large, as is indicated in the last tion in costs parallels the general price levels of the
two columns of table 3-1. In nearly all cases the range locations.
(highest minus lowest) is nearly double the mean. In a A sampling of the most important input costs is
statistical study of this type, such a wide variation is to shown in table 3-2. A wide range is exhibited in three of
be expected and does not present a major problem the main inputs to sanitation systems: unskilled labor,
because the figures are meant to be descriptive rather water, and land. The sensitivity of system costs to
than predictive. Even within a single country, cross- changes in factor input prices is not easy to investigate
community cost differences were apparent when a in a comparative study such as this. The final section of
single technology was found both in urban and rural this chapter, however, presents general conclusions on
areas. Further, the relatively wide margins between the cost sensitivities.
56 ANALYSIS OF FIELD STUDY RESULTS
Table 3-2. Selected Input Costs and Conversion Factors for Sanitation Technologies
(1978 U.S. dollars)
Unskilled Water Land Conversion factors
labor (per cubic (per hect- Capital Unskilled Foreign
Location (daily), meter)' are)c (percent) labor exchange
Botswana 1.80 0.38 100 10 0.7 1 00
Colombia 3.20 0.30 n.a. 12 0.3 1.00
Ghana 5.50 n.a. 65 12 0.8 1.75
Indonesia 1.80 O. lI d n.a. 20 1.0 1.00
Japan 10.50 0.85" n.a. 10 1.0 1.00
Korea 4.00 n.a. n.a. 14 0.8 1.12
Malaysia 3.40 0.35 200 12 1.0 1.00
Nicaragua 2.10 0.13 n.a. 20 0.5c 1.10
Nigeria 3.40 1.60 n.a. 12 0.8 1.15
Sudan 1.90 0139d 100 16 1.0 1.25
Taiwan 3.95 0.40d 800 12 0.9 1.00
Zambia 4.00 0.70 65 12 0.6 1.25
Mean 3.80 0.36 222
Median 3.40 0.39 100
Range 8.70 1.49 735
n.a. Not available.
Source: World Bank country economists and field consultants reporting on case studies. For more detail, see Richard Kuhlthau (ed.),
Appropriate Technology for Water Supply and Sanitation, vol. 6, Country Studies in Sanitation Alternatives (Washington. D.C.: World
Bank, 1980).
a. Market price in studied communities including benefit package where applicable.
b. Average incremental cost (AIC).
c. Estimated opportunity cost; collected in those cases where land costs were part of waste treatment.
d. Average of several community studies.
e. Unskilled rural labor only; for urban unskilled labor, conversion factor is 1.
Investment and recurrent costs from a system with high recurrent cost (such as
vacuum-truck collection) may be large enough to
The distinction between investment and recurrent justify training (or importing) the necessary manage-
costs is an important one for both financial and techni- ment skills.
cal reasons. A city or community with very limited The breakdown for investments and recurrent costs
present fiscal resources but with a good growth poten- for the technologies studied is presented in table 3-3.
tial might find it impossible to raise the investment There is no consistent relation between the overall cost
finance to build a system with large initial capital of systems and their percentage of investment or recur-
requirements, but it could build and maintain another rent costs. The two high-cost and two of the medium-
system (with the same TACH) whose recurrent costs cost technologies exhibit recurrent costs amounting to
were relatively high. Conversely, a major city in a between 20 and 40 percent of TACH. The systems with
developing country that has access to external sources the highest recurrent costs (as a percentage of the total)
of funds might prefer to build an expensive system are in the low-cost group-namely, non-Japanese cart-
initially with the help of grant or low-interest loan age and buckets, with 52 and 43 percent recurrent cost,
capital and possibly reduce its need for recurrent respectively. The lowest percentage recurrent cost sys-
funds.4 tems-pit privies, aquaprivies, and composting latrines
From the technical viewpoint, high recurrent costs -are in the low- and medium-cost groups.
generally stem from large operating and maintenance This somewhat surprising lack of correlation is in
requirements. It may be unwise to opt for a system with part because of the nature of the figure for recurrent
high recurrent costs in those developing countries in cost. Because economic-rather than strictly finan-
which skilled labor is scarce or in which the manage- cial-costs are used in this study, a major item is
ment necessary to coordinate large numbers of un- included in recurrent cost that typically does not appear
skilled workers does not exist. An offsetting benefit to in engineering cost estimates: the water used to flush
this problem is that the employment benefits arising some systems. Although water for flushing is absolutely
THE ECONOMIC COMPARISON 57
necessary for the proper operation of many systems Table 3-4. Percentage Investment and Recurrent
(from sewerage to PF toilets), its cost is often ignored in Cost of Community Sanitation Systems
engineering or financial studies that focus only on those Percentage of total
costs incurred by the utility. In order to see how the
inclusion of the cost of water for flushing would affect Investment Recurrent
the breakdown of investment versus recurrent costs, Technology cost cost
separate calculations excluding water costs were made Sewerage 81 19
for those six systems that require water.'5 Sewered aquaprivy 84 16
The overall conclusion from table 3-3 is that nearly Japanese vacuum-truck cartage 68 32
all of the sanitation systems are relatively high in Other vacuum-truck cartage 48 52
Bucket cartage 57 43
investment, as opposed to recurrent, cost. Only in the Communal toilets 88 12
case of non-Japanese cartage do recurrent costs repre-
sent more than half of TACH. In ten of the twelve Note: Percentages are calculated excluding costs of water used
systems (with the two varieties of septic tank and in flushing.
vacuum-truck cartage taken as separate systems), in-
vestment costs account for more than 60 percent of In that sense, a distinction based on the relative impor-
TACH. If costs of water for flushing are excluded from tance of investment and recurrent costs of different
recurrent costs, as is done in table 3-4, only vacuum- systems becomes moot. Whereas sewerage and PF
truck cartage and bucket systems show recurrent costs toilets both entail recurrent costs of about 30 percent of
of more than 30 percent. their respective TACHs, the important point is that the
There are several implications of this concentration investment cost (per household) of the former is more
in investment costs. One is that there is probably scope than twenty times larger than that of the latter.
for external financing regardless of which technology is Considering only the community systems covered in
chosen by a particular city or community. High initial this study, the distinction between investment and
costs almost invariably require some sort of financial recurrent costs becomes more relevant. The three
mechanism to smooth payments so that they are more cartage systems are much more intensive in recurrent
in line with benefits delivered to (and paid for by) the costs than are the water-carried systems (or even
consumers. A second implication is that, where funding communal latrines) when water costs are excluded. The
constraints are binding, the size of the initial invest- financial result of a system with high investment cost is
ment requirement may be the most important determi- relatively high fixed costs that must be met regardless
nant of technological choice. There is relatively little of how much service is provided (or how many new
scope for substituting a system of higher recurrent cost. connections are made). This can put a real financial
Table 3-3. Average Annual Investment and R'ecurrent Cost per Household for Sanitation Technologies
(1978 U.S. dollars)
Mean Investment Recurrent Percentage of total
Technology TACH cost cost Investment Recurrent
Low cost
PF toilet 18.7 13.2 5.5 71 29
Pit latrine 28.5 28.4 0.1 100
Communal toilet 34.0 24.2 9.8 71 29
Vacuum-truck cartage 37.5 18.1 19.3 48 52
Low-cost septic tank 51.6 40.9 10.7 79 21
Composting toilet 55.0 50.9 4.8 92 8
Bucket cartagea 64.9 36.9 28.0 57 43
Medium cost
Sewered aquaprivy' 159.2 124.6 34.6 78 22
Aquaprivy 168.0 161.7 6.3 96 4
Japanese vacuum-truck cartage 187.7 127.7 60.0 68 32
High cost
Septic tank 369.2 227.3 141.9 62 38
Sewerage 400.3 269.9 130.4 67 33
Negligible.
a. Per capita costs were used and scaled up by the cross-country average of six persons per household to account for large differences
in the number of users.
58 ANALYSIS OF FIELD STUDY RESULTS
burden on the utility or municipality during the early and aquaprivies was for the superstructures, which
years of such a system. It also means that the financial were made of concrete blocks. If these experimental
viability of the utility is extremely sensitive to the units had been built in the rural areas by villagers using
accuracy of the demand forecast. With systems having local materials such as clay brick or straw matting,
high recurrent costs (such as cartage), the response to their cost could have been reduced significantly.
slow growth in demand is delayed investment in new The functional breakdown of costs for the twelve
trucks and fewer new workers hired. With systems systems is given in table 3-5. Even among the six
having high investment costs, however, there is little community systems, on-site costs account for at least 45
scope for reducing costs in response to reduced demand. percent of the total. Japanese and Taiwanese septic
This is perhaps not a major worry in cities that already tanks have the highest on-site costs, over $300 per
have sewerage in some areas, for example, and are household annually. The size of the costs incurred by
ready to expand their system. Here the demand for the the household in total system costs shows the impor-
service has already been tested. In cities of the develop- tance of finding ways for funding on-site facilities. The
ing world, however, where no such service already very low connection rates of many sewerage systems in
exists (and where the ability to pay for the necessary on- developing countries (even when connection is a legal
site investment is limited), it is extremely risky to requirement) can probably be explained by the large
choose a system that has high investment cost on the household expenditure involved.
basis of hypothetical demand projections. In such a Two of the systems, sewerage and vacuum cartage,
case, economies of scale are a two-edged sword. exhibit an interesting variety of cost patterns across the
case studies. The sewerage costs for the eight cities
covered are shown in table 3-6. There is a wide
difference in on-site costs ranging from an average of
The separation of TACH into its functional compo- about $300 per household annually for the Japanese
nents is useful in determining where to direct the design systems to an average of just over $130 per household
effort in an attempt to reduce costs. For most of the annually for the five systems in developing countries.
individual systems, of course, all (or greater than 90 This variation is caused by the more elaborate internal
percent) of the cost is on-site. Thus, an investigation of plumbing facilities that are found in middle-class Japa-
the potential for cost reduction must concentrate on the nese homes and the high cost and relatively large
on-site system components and the materials and meth- amount of flushing water required by the Japanese
ods used to produce and install them. The case study of systems."6 The investment costs of collection for the
Gaborone, Botswana, shows that between 40 and 60 sewerage systems do not fall into any clear groupings
percent of the TACH for pit latrines, composting toilets, but vary with the terrain and population density of the
Table 3-5. Average Annual On-site, Collection, and Treatment Costs per Household
(1978 U.S. dollars)
Mean Percentage of total
Technology TACH On-site Collection Treatment On-site Collection Treatment
Low cost
PF toilet 18.7 18.7 100
Pit privy 28.5 28.5 100
Communal toilet 34.0 34.0 ... 100
Vacuum-truck cartage 37.5 16.8 14.0 6.6 45 37 18
Low-cost septic tank 51.6 51.6 . 100
Composting toilet 55.0 47.0 - 8.0 85 .. 15
Bucket cartagea 64.9 32.9 26.0 6.0 51 40 9
Medium cost
Sewered aquaprivyv 159.2 89.8 39.2 30.2 56 25 19
Aquaprivy 168.0 168.0 100
Japanese vacuum-truck cartage 187.7 128.0 34.0 26.0 68 18 14
High cost
Septic tank 369.2 332.3 25.6 11.3 90 7 3
Sewerage 400.3 201.6 82.8 115.9 50 21 29
* Negligible.
a. Per capita costs were used and scaled up by the cross-country average of six persons per household to account for large differences
in the number of users.
THE ECONOMIC COMPARISON 59
Table 3-6. Annual Sewerage Costs per Household
(1978 U.S. dollars)
On-site
Flushing Collection Treatment
City Investment Recurrent water Investment Recurrent Investment Recutrrent Total
Kyoto, Japan 166.1 41.3 126.4 88.9 12.1 147.1 59.4 641.3
Hannoh, Japan 146.0 45.5 112.8 58.5 13.3 96.0 89.4 561.5
Higashi Kurume, Japan 153.4 37.6 71.3 36.2 3.9 55.4 42.6 400.4
Khartoum, Sudan 89.2 32.3 174.3 8.5 255.0 12.8 572.1
Managua, Nicaragua 80.8 7.1 10.2 105.1 2.6 89.8 28.2 323.8
Ndola, Zambia 105.8 17.6 153.3 23.5 5.9 5.9 5.9 217.9
Malacca, Malaysiaa 98.9 10.3 34.2 56.9 25.1 8.2 9.3 242.9
Gaborone, Botswana 61.4 11.0 40.9 6.6 16.2 6.1 142.2
Negligible.
a. Based on a sewerage master plan.
cities. Recurrent costs of collection are uniformly low. the option of improving their individual facilities as
In treatment costs there is an expected split between their income permits.
those with conventional plants (activated sludge or
trickling filter) and those with ponds. The average
treatment costs of the former are $175 per household Controlled Comparisons
annually, whereas those of the latter are less than $20
per household annually. As mentioned previously, the major disadvantage of
The costs from the case studies involving vacuum- conducting comparisons of technology across locations
truck cartage are shown in table 3-7. The major is that it is difficult to draw conclusions about how
difference between the Japanese systems and the others particular technologies would compare in a given coun-
is in the investment cost to the household. The collec- try or site. Analysis of a single location requires
tion vehicles used in Japan are more expensive than controlled tests. Fortunately, the present study did
those used elsewhere, and labor costs for vehicle opera- include selected cases in which various technologies
tion and maintenance are much higher. These two were competing within a small geographic area. These
factors, however, are far outweighed by the very large cases still do not yield the sort of precision that could be
differential in household facility costs. This has impor- obtained with purely synthetic examples because even
tant implications for the upgrading of cartage systems. adjacent areas are not identical. An offsetting advan-
As long as the utility provides efficient and hygienic tage of using actual case data, however, is that these
vacuum-truck collection, individual households have data do include the imperfections (for example, low use
Table 3-7. Annual Vacuum Cartage Costs per Household
(1978 U.S. dollars)
Costs
Population On-site Collection Treatment
served On-site Collection Treatment
City (thousands) Investment Recurrent Investment Recurrent Investment Recurrent Total
Kyoto, Japan 1,462 92.5 18.5 6.1 35.3 15.3 4.1 171.8
Hannoh, Japan 56 113.3 22.7 7.5 43.2 18.7 5.0 210.4
Higashi Kurume, Japan 103 118.2 18.8 3.8 16.5 16.9 18.0 192.2
Tatayama, Japan 57 106.3 20.0 3.3 21.2 8.9 16.8 176.5
Keelong, Taiwan 342 9.6 2.2 1.9 12.2 3.9 2.4 32.2
Tainan, Taiwan 85 9.6 2.2 2.2 15.3 29.2
Pingtung, Taiwan 175 9.6 2.2 0.8 8.1 2.4 2.6 25.7
Chuncheon, Korea 141 20.9 6.6 0.1 5.7 5.0 8.1 46.4
Malacca, Malaysiaa 95 13.5 7.8 3.9 19.9 7.3 1.4 53.8
* Negligible.
a. Based on a hypothetical system design.
60 ANALYSIS OF FIELD STUDY RESULTS
of capacity or poor equipment maintenance) that might Malacca, a city of about 90,000 in Malaysia.'9 Cur-
not be built into a model. Two controlled comparisons rently the city is served by a combination of bucket
are discussed below: one between sewerage and cartage latrines, septic tanks, PF toilets, and privies that directly
systems in the same cities and one between four on-site overhang the river. The wastes from kitchen and bath
technologies and sewerage. are discharged to open, surface water drains. A sewer-
age master plan was prepared for the city in 1968,
Sewerage versus cartage but-because of lack of money, potential technical
Three of the Japanese communities studied were problems stemming from a high water table, and
served by both sewerage and vacuum-truck cartage. In community dissatisfaction with the proposed marine
Kyoto and Higashi-Kurume, about 45 percent of the outfall-there has been no follow-up implementation of
population are connected to public sewers and an equal the study's recommendations. A Malaysian engineer
number enjoy vacuum-truck collection. In Hannoh, who was familiar with the local conditions and history
n was asked to prepare an alternative master plan to serve
nearly 60 percent are served by vacuum trucks, 15ppp
percent by sewerage (with the rest using individual the city with vacuum-truck collection and to compare
systems). The TACHs of the two systems in the three the costs with those of the sewerage study (adjusted for
cities are as follows (TACHs are in U.S. dollars): inflation).
The annual costs of waste disposal per household for
TACH the two systems in Malacca are shown in table 3-8.
Total annual sewerage costs are nearly five times
KySto 641.3 171C 8 greater than cartage costs. No social weighting for
Higashi-Kurume 400.4 192.2 employment benefits has been used in calculating these
Hannoh 561.5 210.4 costs, but the cartage system would employ more than
Average 534.4 191.5 twice as many people as the sewerage system, including
In Kyoto, where sewerage is especially expensive 100 general laborers (compared with 14 for sewerage).
(partly because of the high average incremental cost of
water), cartage costs only about one-fourth as much per On-site systems
household. In the other two cities, cartage costs are A controlled cost comparison of on-site systems is
about half those of sewerage.'7 possible with the results of the study of Gaborone,
There is a growing demand on the part of household- Botswana. The International Development Research
ers in Kyoto for the sewer system to be extended to Centre sponsored an experimental latrine program in
areas presently served by night-soil collection. Because Botswana to build and monitor a variety of on-site
the tabulation above shows that sewerage costs nearly designs. The four designs that performed best were
four times as much as cartage, it might seem that costed for inclusion in this study. While the costs for all
people who can afford it value the increased conve- systems appear high relative to those for similar sys-
nience of sewerage at least as much as the difference in tems in other countries, this should not affect the
cost. But it is worth repeating that the costs developed relative comparison of technologies. The high costs are
in this economic comparison reflect real resource costs
to the economy, not financial costs actually charged to
households. In Japan, as in many other locations, the Table 3-8. Comparative TA CHs of Sewerage
construction costs of sewers and treatment facilities are and Vacuum-truck Cartage in Malacca, Malaysia
heavily subsidized by the national government. In (1978 U.S. dollars)
addition, the city of Kyoto provides municipal loans at TACH Sewerage Cartage
no interest for the installation of a flush toilet and
indoor plumbing. In addition, the sewerage authority in On-site
Kyoto operates at a substantial loss (based on its Investment 98.9 13.5
sewerage revenues). In fiscal year 1976, subsidies from Recurrent 43.5i 7.8
Collection
other city accounts represented 47 percent of the Investment 56.9 3.9
sewerage authority's total revenues. Thus, the financial Recurrent 25.1 19.9
cost of sewerage (and also of cartage) in Kyoto to the Treatment
householder significantly understates its true economic Investment 8.2 7.3
cost.'8 Recurrent 9.3 1.4
A more detailed controlled comparison between Total 242.9 53.8
sewerage and vacuum-truck cartage was carried out for a. Includes S34.2 for water used in flushing.
THE ECONOMIC COMPARISON 61
because of the pilot nature of the project, the difficulty Benefits from Reuse
of obtaining even simple inputs (such as cement)
locally, and some overdesign (particularly in the super- As discussed earlier in this chapter, it is assumed in
structure) of the systems. this study that the major benefits of sanitation systems
The results of the costing analysis for ventilated are related to health and convenience and therefore
improved pit (vIP) latrines, aquaprivies, double-vault cannot be meaningfully quantified. Some of the tech-
composting (DVC) latrines, and Reed Odorless Earth nologies studied, however, provide economic benefits in
Closets (ROECs) in Gaborone are shown in table 3-9. To the form of fertilizer or biogas, to which a monetary
enable a better comparison with the cost of sewerage in value can be assigned.2 One of the original aims of this
Gaborone, the cost of substructures alone are also study, in fact, was to determine the scope for offsetting
shown. On a household basis, the VIP and the ROEC are sanitation costs with reuse benefits. .
by far the cheapest. The substructure cost of the DVC Unfortunately, it has been very difficult to locate in
latrine is about 80 percent more. The aquaprivy cost developing countries working examples of human waste
(substructure) is more than double that of the VIP or disposal systems with a sizable reuse component. A few
ROEC, whereas sewerage costs are almost seven times of the sewage treatment systems produce small
higher. amounts of methane from their digesters, and this is
No analysis of the benefits derived from the compost used for heating. There is some demand from orchard
eventually available from the DVC was possible because farmers in Korea for the night soil collected by vacuum
all experimental units were recently constructed. De- truck, but the municipality makes no effort to set up a
sign parameters suggest that the DVC would require delivery system or to charge a market-clearing price.
emptying only at five-year intervals, so that the amount The composting latrines built in Botswana are too new
of compost available (per household annually) is likely to yield useful data on reuse. All except one of the
to be small. A firm analysis of the benefits from biogas units observed ran on animal, rather than
composting cannot be undertaken until more opera- human, waste. In short, although there is much experi-
tional experience is available. It is unlikely, however, mental and theoretical information on the economic
that such benefits would affect the net cost ranking of potential of reuse technologies, there is a dearth of
these alternatives. empirical data on actual experience.2"
The conclusions from these three exercises in con- All of the significant reuse technologies found in this
trolled costing are in line with those of the cross- study were located in the Far East. Biogas plants were
country, comparative analyses of technologies. Sewer- found at the household level on the island of Taiwan
age costs are at least twice and generally four to five and in Korea. Municipal systems involving reuse of
times as large as those of well-run, vacuum-truck human excreta as an input into agriculture and aqua-
cartage systems. On-site technologies can effect even culture were found on the island of Taiwan and, to a
larger savings, particularly if superstructure costs can lesser extent, in Indonesia. In none of these cases was
be kept low. the reuse element developed to its full potential through
marketing analyses or optimal pricing strategies. The
cases described below, therefore, should not be taken as
examples of how much (or, more accurately, how little)
reuse benefits can affect the economics of sanitation.
Table 3-9. Comparative TACHs of On-site Systems
and Sewerage in Gaborone, Botswana Biogas
(1978 U.S. dollars)
Annual There were about thirty family-size biogas units in
substructure operation in one of the communities on the island of
cost per Taiwan studied in 1977. Each biogas unit consisted of a
Technology TACH household 6-foot diameter, excavated digester with an inverted
Ventilated improved pit (vip) latrine 56.2 21.3 steel lid that floated up and down on a water seal. The
Reed Odorless Earth Closet (ROEC) 56.2 21.3 methane generated was transported to the kitchen
Double-vault composting (DVC) through a pressure hose connected to the outlet pipe at
latrine 74.6 38.6 the top of the inverted lid. The digester was emptied
Aquaprivy 87.7 50.6 twice a year, and the sludge was sold to neighboring
Sewerage > 142.2a 142.2 farmers. All of the digesters studied ran on a mixture of
a. Superstructure costs are included in the house construction. human and animal wastes. The usual input to a unit was
62 ANALYSIS OF FIELD STUDY RESULTS
the night soil from five persons and the manure from capital can be made available or less expensive designs
five pigs. This input loading produced sufficient gas for developed. The requirement for such large volumes of
cooking purposes all year for a family of five, a animal waste is also likely to exclude the lowest income
replacement for the 20-kilogram cylinder of liquid classes, who generally do not own animals (or land on
petroleum gas formerly purchased each month. The net which to build the digester). Furthermore, that this
cost of a typical biogas unit on the island of Taiwan is biogas unit is economically attractive on a household
shown in table 3-10. scale does not imply that it would be advantageous on a
This net cost does not represent the full cost of the community scale. Aside from the technical questions of
total system of hog raising-excreta disposal-biogas the economies of scale of the digester itself, the collec-
production. It has been developed within the more tion and transportation of human and animal wastes to
limited framework in which the "with and without" a single point and the subsequent redistribution of gas
cases are defined as with and without the latrine would involve large capital outlays and operating re-
equipped with biogas digester. Thus, the cost of hog quirements that are avoided by a single-family unit
feed and upkeep is not included, nor is the benefit from located in the courtyard of the house.
the sale of the animals. For purposes of comparison A second case of household biogas production was
with costs of other sanitation systems, this is the observed in Korea. There, the family claimed to be
appropriate method to employ. For a complete project using only human excreta and kitchen wastes to stock
appraisal, however, it would be inadequate. This point the unit. It produced sufficient gas to satisfy all of the
was demonstrated on the island of Taiwan by the cooking needs during nine months of the year. Insuffi-
marked decline in the number of household biogas units cient cost data were available, however, to permit a
in the last five years because of the large increase in the calculation of net cost.
price of animal feed, which has made hog raising
uneconomic. Agricultural reuse
In addition, although the net cost of this sanitation Reuse of composted night soil as fertilizer is also
system is attractively low compared with that of the practiced at the household level in rural areas of Korea.
other units considered above, its initial investment cost The large size of household pit privies in two rural
is very high. In a subsistence economy, large investment villages studied was puzzling until it was discovered
costs may present an insurmountable obstacle to the that the farmers deposited the animal wastes from
adoption of a low-cost system unless subsidized loan nearby cattle pens into the pits and then allowed the
entire quantity to "compost" over a six- to twelve-
month period before spreading it on the vegetable fields
Table 3-10. Net Cost of Household Biogas Unit, and orchards. Based on the Korean government's im-
Island of Taiwan puted cost of such organic fertilizer, the composting
(1978 U.S. dollars) operation yielded the farmer an annual net benefit of
$37 on an annual cost of $34. These figures do not
Item cost cost (years) include any cost for the farmer's time in digging out the
latrine and transporting the compost to the field.
Cost Nonetheless, they indicate the potential for agricul-
Construction, 236.0 31.6 20 tural reuse at the household level in rural areas.
Land (for 15 square At the community level, again, very few data are
meters) 348.0 41.8 Infinite available. In Chuncheon, Korea, some of the night soil
Annual desludgmng 16.6 16.6
collected by vacuum truck is sold to farmers (before
TACH 90.0 treatment) for about $7.00 per truck (or $3.50 per
cubic meter). At this rate, demand is sufficient to
Benefit absorb about half of the night soil produced by the city.
Biogas (12 cylinders of Because the demand is seasonal, however, the night-soil
liqud petroleum 75.0 - treatment plant, which was designed for peak volumes,
Sludge sales (2 carts) 11.0 _ operates inefficiently during the spring and summer
months. There is very little net benefit, therefore, to the
Net annual cost per city (about 3 percent of the cost on an annual basis)
household 4.0 from the sale of untreated night soil, and the health
- Not applicable. hazards to the farmer from handling it are probably
a. Includes household latrine facilities. considerable. If a simple composting treatment plant
THE ECONOMIC COMPARISON 63
had been built instead of the two-stage digester, a ment's equity goals and the degree of distortion in other
market for treated night soil might have developed that prices in the economy. This correspondence could be
would have minimized sanitation costs to the commu- accomplished with sewerage, for example, by setting a
nity while providing a safe and valuable product to surcharge on the water bills of connected consumers
nearby farmers. that is equal to the AIC of sewerage per cubic meter of
water consumed.22 In the case of most on-site systems,
the consumer would pay to construct the original
Aquacultural reuse facility (either initially or through a loan at an interest
The best case study involving community-scale reuse rate reflecting the opportunity cost of capital) and then
was conducted in Tainan on the island of Taiwan. Both pay a periodic sum to cover the facility's operation and
public and private night-soil collectors operate there, maintenance expenses (if any). In cases such as these,
and untreated night soil is sold primarily to fish the financial cost would be identical to the economic
farmers. The private collectors work only during the ten cost except for any taxes and shadow pricing of inputs
months of the year in which there is a demand for night that must be purchased in the market.23 To the extent
soil. The public system, of course, operates year-round that they account for a significant part of total eco-
and is able to sell about 80 percent of its total collection. nomic costs, financial costs may be above or below
The public system charges $0.65 per ton plus $0.57 per economic costs.
kilometer for transportation costs, whereas the private In deriving financial costs in any particular case, it is
collectors charge $7.00 per ton inclusive of transporta- necessary for the analyst to consult with officials of the
tion (most trips were less than 10 kilometers). central and local government to determine their finan-
No investment or operating costs were available on cial policies and noneconomic objectives. If the govern-
the private collectors. The TACH of the public system ment places a high priority on satisfying the basic needs
was $28.85, and the sale of night soil during the ten of all of its citizens, then it may be willing to subsidize
months of the year yielded $1.28 on a household basis. part or all of the construction costs of a simple sanita-
Because the private operators presumably earn a posi- tion system. The general policy of international lending
tive income on their operations, the public system must agencies such as the World Bank is that, if the cost of
either incur significantly higher costs or charge too the minimal sanitation facility necessary to permit
little for its product, or both. adequate health is more than a small part of the
household income of the lower income consumer (say,
5-10 percent), then the central or local government
should attempt to subsidize its construction to make the
Financial Implications facility affordable. If, however, some consumers wish to
have better or more convenient facilities, they should
The purpose of deriving economic costs is to make a pay the additional cost themselves. Similarly, if more
meaningful, least-cost comparison among alternatives. affluent communities decide that, beyond meeting
Such a comparison is extremely useful to the planner basic health needs, they wish to safeguard the cleanli-
and policymaker. The consumer, however, is much ness of their rivers or general environment by building a
more interested in financial costs-that is, what he will more expensive sanitation system, then they should pay
be asked to pay for the system and how the payment will for that system either through direct charges to users or
be spread over time. The difficulty in developing through general municipal revenues. Because the ma-
financial costs is that they are entirely dependent upon jority of the poorest people in most countries live in
policy variables that can change dramatically. rural areas, it is usually not appropriate to subsidize
Whereas economic costs are based on the physical urban services from national tax revenues.
conditions of the community (for example, its abun- Because financial costs are dependent upon policy
dance or scarcity of labor, water, and so forth) and are decisions, it is not possible to present comparable
therefore quite objective, financial costs are entirely financial costs of the various technologies in the same
subject to interest-rate policy, loan maturities, central way that economic costs can be developed. It is,
government subsidies, and the like. The financial cost however, possible to use the economic costs to derive
of a sewerage system for a community can be zero if the total investment costs per household that will provide a
central government has a policy of paying for such basis for the financial comparison of alternatives. The
systems out of the general tax fund. other useful figure to be extracted from economic costs
To promote the economically efficient allocation of is the annual recurrent cost (with water costs shown
resources, financial costs should certainly reflect eco- separately), which will give an indication of periodic
nomic costs as closely as possible, given the govern- financial requirements.
64 ANALYSIS OF FIELD STUDY RESULTS
The financial requirements for the various low-, lute level is less relevant than their relation to other
medium-, and high-cost systems examined are given in recurrent charges. In addition, it was not possible to use
table 3-1 1. The first column shows the total investment market prices for water in the various communities
cost (including on-site, collection, and treatment facili- because of different charging systems and, for some
ties) divided by the number of households to be served. cases, lack of data.
For the individual household systems (such as pit It is difficult to draw conclusions from the financial
latrines), the investment cost is simply the total cost of requirements because of the reasons of noncomparabil-
constructing the facility. For the community systems, it ity mentioned above. Some standard loan terms, how-
is the total cost divided by the design population ever, were assumed in order to derive one possible set of
(number of households). Thus, for those facilities that financial costs (shown in the fourth column of table 3-
exhibit economies of scale, such as sewage treatment 11). Because the length of loans is generally related to
plants, this figure will understate the real financial the life of facilities financed, loan periods of five, ten,
requirements during most of the early years of opera- and twenty years were used for the low-, medium-, and
tion. Note that because investment costs do not reveal high-cost systems, respectively. An 8 percent interest
anything about the lifetime of facilities they should not rate (well below the opportunity cost of capital in most
be used to make judgments about least-cost alterna- countries) was used as a representative interest charge
tives. They are presented only to indicate an order of for loan funds to a utility. Financial affordability can be
magnitude of the initial financial expenditure neces- roughly tested by comparing financial costs to house-
sary for the various systems. hold income (see the table's fifth column). Average
The monthly recurrent cost per household (second income per capita in the low-income countries (where
column of the table) is the sum of recurrent costs for on- the bulk of the water and sanitation deficiencies exists)
site, collection, and treatment facilities excluding costs was about $180 in 1978. With an average of six persons
for water used in flushing, which are presented sepa- per household, this yields a monthly household income
rately in the third column of table 3-11. Because water of $90. All of the medium- and high-cost systems have
charges vary so much from one community to another monthly costs that amount to over 10 percent of income
(both for economic and financial reasons), their abso- and, thus, are probably outside the range of affordabil-
Table 3-11. Financial Requirements for Investment and Recurrent Cost per Household
(1978 U.S. dollars)
Percentage of income
Total invest- Monthly recur- Monthly water H,ypothetical total of average low-
ment cost rent cost cost monthly cost income householdb
Technology (1) (2) (3) (4) (5)
Low cost
PF toilet 70.7 0.2 0.3 2.0 2
Pit latrine 123.0 - 2.6 3
Communal toilet, 355.2 0.3 0.6 8.3 9
Vacuum-truck cartage 107.3 1.6 3.8 4
Low-cost septic tank 204.5 0.4 0.5 5.2 6
Composting toilet 397.7 0.4 8.7 10
Bucket cartage' 192.2 2.3 5.0 6
Medium cost
Sewered aquaprivy 570.4 2.0 0.9 10.0 11
Aquaprivy 1,100.4 0.3 0.2 14.2 16
Japanese vacuum-truck
cartage 709.9 5.0 13.8 15
High cost
Septic tank 1,645.0 5.9 5.9 25.8 29
Sewerage (design population) 1,478.6 5.1 5.7 23.4 26
Negligible.
a. Assumes that investment cost is financed by loans at 8 percent over five years for the low-cost systems. ten years for the medium-
cost systems. and twenty years for the high-cost systems.
b. Assumes that average annual income is $180 per capita, with six persons in a household.
c. Based on per capita costs scaled up to household costs to account for multiple household use in some of the case studies.
THE ECONOMIC COMPARISON 65
ity without further subsidy. Sewerage and the Japanese access for rodents and scorpions during the night and
and Taiwanese septic tanks have recurrent costs that embarrassed users (whose feet could be seen while they
alone are over 10 percent of income, even if initial used the latrine, a matter of sensitivity in this culture).
facilities could be provided free of charge by the Such unimportant details from the technical viewpoint
government. For most of the other systems, affordabil- are often highly significant if health and aesthetic
ity hinges on the arrangements that can be made to benefits (both of which generate a willingness to pay on
subsidize investment costs froi.m other revenue sources. the part of the user) are to be fully realized.
Such arrangements, however, are probably not replica- A final caution is appropriate for the interpretation
ble on a wide scale. Furthermore, average figures of per of the costs developed by these case studies. In very few
capita income should not be relied upon without a cases were the systems optimally designed. This point
recognition of their limitations in countries in which has already been made with respect to the overdesigned
much of the economy is nonmonetized. In addition, superstructure of the Botswana latrines and the reuse
many developing countries in Africa and Asia have per components found in the East Asian countries. It is also
capita incomes that are less than the average of the low- true of the sewered aquaprivies in Zambia (which fed
income group used here, and, in all of the countries, into collectors of conventional size designed for a full
more than half of the population earns less than the sewerage system) and most of the other cases. Never-
country average. theless, the broad ranking of technologies, the patterns
of cost sensitivity, and the method used to arrive at
appropriate figures for a least-cost comparison are all
Conclusion believed to have general applicability.
It may be useful to summarize some broad conclu-
sions from this review of cost data. Precise calculations Notes to Chapter 3
of the sensitivity of system costs to changes in particular
parameters are impossible to generate within the 1. Variations of this calculation include the internal rate of return
framework of an empirically based study such as this. and the net present value. For a discussion of the set of conditions
Yet it is possible to discern areas of relatively greater under which each is appropriate, see Lyn Squire and Herman G. van
and lesser importance. der Tak, Economic Analysis of Projects (Baltimore: Johns Hopkins
The two most outstanding influences on total house- University Press, 1975), pp. 39-43.
hold costs are factors that have often been ignored in 2. Ibid
engineering analyses: on-site household costs and the 3. H. Shipman and others, "Measurement of the Health Benefits
of Investments in Water Supply, " Public Utility Note 20 (Washing-
costs of water used for flushing in water-carried sys- ton, D.C.: The World Bank, Transportation, Water, and Telecommu-
tems. The former is important in all systems and, in the nications Department, January 1976; processed).
cases studied, never accounted for less than 45 percent 4. See Squire and van der Tak, Economic Analysis of Projects, pp.
of TACH. The latter is most important for sewerage and 99-132, for a description of the data requirements and methods of
septic tank systems. When the economic cost of water is computing conversion factors.
high, the payoff from designing systems with low 5. For example, in one Islamic country market interest rates are
requirements of flushing water is large.24 set by law at 3 percent, whereas the opportunity cost of capital has
been estimated at 16 percent. With such a wide discrepancy, it is very
A further implication relates to those aspects of likely that the least-cost alternative using the market discount rate
sanitation systems that do not significantly influence would be much more capital intensive than that selected by an
costs but can make a big difference in benefits. Two economic least-cost analysis.
components of individual systems-ventilation stacks 6. This percentage is based on data from developed countries,
and water seals-aid greatly in reducing odors and fly which show that the water used to flush toilets is around 40 percent of
breeding without adding significantly to system costs. total domestic water use (excluding garden watering).
In one of the Latin American case studies, it was found 7. See R. J. Saunders, J. J. Warford, and P. C. Mann, Alternative
Concepts of Marginal Cost for Public Utility Pricing: Problems of
that people were very concerned about the color of the Application in the Water Supply Sector, World Bank Staff Working
floors of their latrines. Although this preference is an Paper, no. 259 (Washington, D.C.: The World Bank, May 1977).
aesthetic matter without technical importance, it may 8. This degree of risk can be explicitly built into the alternative
make the difference between a facility that is kept clean selection process. Suppose technology A yields a net present value of
and is regularly used and one that is not. In another case I 00 and technology B one of 90, given the demand forecast. There is a
the latrine designers, in an effort to cut costs, had used 30 percent probability that the forecast is too high and a 10 percent
pr.'ut shes o, z. T probability that it is too low. If it is too high, technology A's net
precut sheets of zinc for the superstructure siding. ThIs present value drops to 30 because of its large unused capacity during
meant, however, that the siding did not reach all the the early years, whereas technology B can be modified to cut costs so
way to the floor-a design flaw that provided easy that its net present value falls only to 70. If demand is too low, A's net
66 ANALYSIS OF FIELD STUDY RESULTS
present value falls to 90 and B's falls to 85. The weighted average, or because the opportunity cost of capital does not depend on the source
expected value (E), of the net present value of the two technologies of the funds or the terms of a particular loan package.
can be calculated as follows: 15. As would be expected, those systems requiring the most
EA = 0.3(30) + 0.1(90) + 0.6(100) = 78.0 flushing water are most affected by the change. The recurrent cost
A 037)+018)+069) 85.component of sewerage systems drops from 33 to 19 percent, whereas
EB 0.3(70) + 0.1(85) + 0.6(90) 83.5. that of septic tanks falls from 36 to 24 percent.
Given the uncertainty attached to the demand forecast, technology 16. Twenty liters per flush compared with 8-15 liters in the other
B should be selected because the expected value of its net present countries.
value is higher than that of technology A. If the demand forecast were 17. In all three cities the night soil from the cartage systems is
certain, technology A would have the higher net present value. treated by dilution and transferred to the sewage treatment plant. It
9. The environmental cost of depositing sullage into nearby is likely that cheaper treatment methods could be used in cities
watercourses must, of course, also be assesssed. The limited informa- without sewerage systems.
tion available on the composition of sullage wastes suggests that its 18. See chapter 6 for a discussion of the effect of such policies on
health hazard is low. This should also be assessed, however, for the the choice of appropriate technologies.
site in question. 19. We are indebted to Mr. Ng Kin Seng for this comparison. A
10. The development of low-water-use appliances, such as show- summary of his report is included in Kuhlthau (ed.), Country
ers, is a very promising means of realizing sanitation cost savings. Studies.
Reducing the amount of sullage water to be disposed of not only saves 20. Other potential reclamation benefits include stock and garden
water but also extends the range of applicability for on-site disposal watering with sullage and irrigation with sewage.
systems.wtrn
21. The obvious exception to this statement is the experience of
I1. All costs presented in this chapter are in 1978 prices and U.S. China, but scientific documentation of Chinese experience is rare,
dollars. For price and foreign exchange conversion factors for each and it was not possible to include first-hand observation inthisstudy.
country studied, see Richard Kuhlthau (ed.), Appropriate Technol- Many data are also available on biogas production in India, but most
ogy for Water Supply and Sanitation, vol. 6, Country Studies in units use animal instead of human excreta.
Appropriate Sanitation Alternatives (Washington, D.C.: The World 22. Suppose, for example, that the AIC of sewerage is S1.00 per
Bank, 1980). cubic meter of sewage collected and treated. Because water rather
12. The anomalies introduced by aggregating across countries are than sewage is metered, this AIC must be related to the water
illustrated by a comparison of the TACHs of the pit latrine and PF consumed. If, for a given city, sewage flows are 75 percent of water
toilet in table 3-1. The mean cost of the former in the seven cases consumption, then the sewerage surcharge should be $0.75 per cubic
studied was higher than that of the latter in its three case studies. Yet meter of water consumed.
it is clear that, on any one site, a pit latrine would be cheaper than a PF 23. Note that the shadow price of capital may be reflected in the
toilet because of the extra components and water required for the financial cost by using it as the interest rate at which money is loaned
latter. to construct facilities. If market rates are lower, however, the
13. The rankings within the groups should not be taken too consumers will presumably borrow the money elsewhere and pay for
seriously, however. For example, the mean TACH of sewered aqua- the new facility immediately. Shadow rates for labor and water (the
privies is lower than that of nonsewered aquaprivies, but this is other important inputs in this analysis) cannot be incorporated into
because of the very high cost of the Sudanese aquaprivy, which is financial costs if the consumer pays for them separately.
nonsewered. 24. The savings would be even larger if the improved designs for
14. Note that this would not be an economically efficient solution facilities led to the redesign of water distribution networks.
4
Public Health Aspects
IMPROVED COMMUNITY HEALTH is generally consid- developed an environmental classification of excreta-
ered the major benefit of improved sanitation. As the related infections that, together with a basic under-
discussion in the previous chapter has indicated, how- standing of the epidemiological factors important in
ever, it has so far been impossible to determine precisely disease transmission, should enable the planner and
how much improvement in health in a given community engineer to maximize the health benefits of whatever
can be attributed directly or indirectly to a sanitation technology is chosen. The means of doing so include
improvement. Even if a figure for the health improve- both the incorporation of specific features that inhibit
ment could be agreed upon (for example, x fewer man- disease transmission in the design of sanitation facili-
days of sickness annually), it is very difficult to assign a ties and the supplementation of "hardware" with care-
meaningful economic value to it. Much of the illness fully directed educational campaigns.
without the sanitation improvement would have been
borne by children and others unemployed in the mone-
tary sector. The noneconomic value to society of their Water and Health
improved health may be equal to that of an employed
adult, but the economist has no way of quantifying such Although the primary concern of the present study is
a nonmarket value. Moreover, of those man-days of sanitation, the relation between water and health
illness incurred by the employed population, some should be kept in mind.2 Water is important to health in
(perhaps all) work is probably made up at no cost to two ways: contaminated water or insufficient amounts
society during the days following absence because of of water for personal hygiene can be a direct cause of
illness. To use an entire daily wage to value saved man- disease; and the disposal of sullage (wastewater or
days of illness is almost certainly an overestimate. greywater, see chapter 2, the section "Sullage Dis-
These inherent limitations of the health sciences in posal") can, theoretically, serve as a transmission
quantifying the effects of environmental changes on vehicle for some kinds of disease. For these reasons, not
community disease profiles, and of economics in quan- only poor water quality, but also too little and too much
tifying benefits that have no market value, combine to water consumption, present problems.
frustrate the measurement of health benefits. Available evidence indicates that most of the health
Fortunately, the measurement of benefits is not the benefits from safe water are attainable at service levels
primary objective of improved sanitation; achieving the of 30-40 liters per capita daily on site. These service
benefits is. If funds are inadequate to build and main- levels will provide protection against the range of
tain the elaborate sewerage systems known to provide water-related diseases and are adequate for the
all these benefits, then it is essential to choose the personal hygiene that will lead (with health education)
alternative technology that will maximize the health to a lowered incidence of diarrheal disease and skin and
benefits achieved with the available funds. This effort eye infections. For the latter group, access to water is
requires a more precise analysis of the relations be- more important than its microbiological or chemical
tween disease and sanitation than has been attempted quality. In addition, concentrations of chemicals in
in the past. Toward this end, consultants from the Ross drinking water in developing countries sometimes ex-
Institute of Tropical Hygiene of the London School of ceed the published standards or guidelines, which were
Hygiene and Tropical Medicine were contracted, as developed in industrial countries. For example,
part of this study, to focus specifically on the transmis- groundwater in southern Africa containing several
sion process of excreta-related diseases and to investi- hundred milligrams of nitrate per liter is used for
gate the relation of the various sanitation technologies domestic supply, even though the concentration is an
described in chapter 2 to this process.' They have order of magnitude greater than the 45 milligrams per
67
68 ANALYSIS OF FIELD STUDY RESULTS
liter of the World Health Organization (WHO) stan- animals serve as a reservoir, however, are included.
dard. This standard was developed in industrial coun- Second, excreta relate to human disease because
tries to eliminate the risk of methemoglobinemia ("blue their disposal sometimes encourages the breeding of
baby syndrome") in bottle-fed infants, but may be less insects. These insects may be a nuisance in themselves
applicable in areas where infants are breastfed. (flies, cockroaches, mosquitoes); they may mechani-
The fecal hazard of sullage has yet to be demon- cally transmit excreted pathogens either on their bodies
strated. Crude estimates-based on data from the or in their intestinal tracts (cockroaches and flies); or
United States and assuming a high value of 150 liters they may be vectors for pathogens that circulate in the
per capita daily of sullage-indicate that per capita blood (mosquitoes).
discharges of the indicators of bacterial pollution, fecal In considering the transmission of excreted infec-
coliforms and fecal streptococci, in sullage are 106 and tions, the distinction between the state of being infected
105 bacteria per day, respectively.3 Corresponding per and the state of being diseased must be kept in mind.
capita discharges in feces are approximately 100 for Very often the most important group of the population
fecal coli and 109 for fecal streptococci, some four or involved in transmitting an infection shows little or no
five orders of magnitude greater than those for sullage. sign of disease; conversely, individuals with advanced
This means that, even though ratios of pathogens to states of disease may be of little or no importance in
indicators may be higher for sick people than for transmission. A good example occurs in schistosomia-
healthy ones, relative risks of infection from night soil sis, where as much as 80 percent of the total output of
or sewage are four or five orders of magnitude greater. schistosome eggs in feces and urine reaching water
This is consistent with the results of the inquiry into from a human population may be produced by children
possible differences in health profiles between people five to fifteen years old. Many of these children will
living in areas served by sewers and in adjacent areas show minimal signs of disease; conversely, middle-aged
with night-soil collection and sullage discharge to people with terminal disease conditions may produce
surface drains (reported in chapter 2). few or no viable eggs.
Some concern has been expressed over a possible If an excreted infection is to spread, an infective dose
contribution of sullage to increased populations of the of the relevant agent has to pass from the excreta of a
Culex pipiens mosquito, which breeds in polluted water case, carrier, or reservoir of infection to the mouth or
and is a vector of filariasis. The potential importance of some other portal of entry of a susceptible person.
sullage to mosquito breeding is determined by environ- Spread will depend upon the numbers of pathogens
mental factors in which low aridity (see maps 7-9, excreted, upon how these numbers change during the
chapter 2) and local soil permeability would permit the particular transmission route or life cycle, and upon the
water to remain on the surface long enough to permit dose required to infect a new individual. Infective dose
mosquito breeding. Where there are extended periods is in turn related to the susceptibility of the new host.
of relative drought (see maps 4-6), surface impound- Three critical factors govern the probability that, for a
ments of sullage could contribute to extending periods given transmission route, the excreted pathogens from
during which mosquitoes normally breed. one host will form an infective dose for another. These
In sum, although disposal of large amounts of sullage are latency, persistence, and multiplication. Diagram-
resulting from high water service levels may be pro- matically, the concepts can be represented thus:
vided by sewerage in densely populated areas, in areas
of lower water consumption or lower population density Latency
the problem of sullage is one of lower priority. EXCRETED LOAD - Persistence - INFECTIVE DOSE
Multiplication
There is wide variation in the excreted load of
Excreted Infections pathogens passed by an infected person. For instance, a
person infected by a small number of nematode worms
Excreta are related to human disease in two ways. may be passing a few eggs per gram of feces, whereas a
First, the agents of many important infections escape cholera carrier may be excreting more than 106 Vibrio
from the body in the excreta and thence eventually cholerae per gram, and a case may pass I0O3vibrios per
reach others. These are the excreted infections. In some day.
cases the reservoir of infection is almost entirely in Where large numbers of organisms are being passed
animals other than man. These are not considered here in the feces they can give rise to high concentrations in
because such infections cannot be controlled through sewage. Thus, even in England, where water use is
changes in practices of human excreta disposal. A relatively high and salmonellosis relatively rare, raw
number of infections for which both man and other sewage may contain 104 salmonellae per liter. At these
PUBLIC HEALTH ASPECTS 69
concentrations, removal efficiencies of 99 percent in Among the helminths transmitted by excreta, all the
conventional sewage treatment works will still leave 1 02 trematodes infecting man undergo multiplication in
pathogenic organisms per liter in the effluent, and the aquatic snails. This introduces a prolonged latent
implications of these organisms for health will depend period of a month or more while development is taking
upon their ultimate disposal, their ability to survive or place in the snail, followed by an output of up to several
multiply, and the infective dose required. thousand larvae into the environment for each egg that
Latency is the interval between the excretion of a reached a snail.
pathogen and its becoming infective to a new host. In principle, from a knowledge of the output of
Some organisms-including all excreted viruses, bacte- pathogens in the excreta of those infected, the mean
ria, and protozoa-have no latent period and are infective dose, and the extractive efficiency of the
immediately infective when the excreta are passed. The excreta treatment process, simple calculation should
requirements for the safe disposal of excreta containing enable one to assess risk. In practice, disease transmis-
these agents are far more stringent than for those sion is much less predictable than this because of the
helminthic infections in which there is a prolonged variable infective dose of most pathogens and the
latent period. In particular, infections that have a uneven distribution of infection in the environment.
considerable latent period are largely risk free in areas Whereas the minimal infective dose for some diseases
where night soil is being carted by vacuum truck, may be a single organism, or very few, the doses
whereas the others constitute a major health hazard in required in most bacterial infections are much higher.
fresh night soil. Therefore, in the environmental classi- Data bearing on this are very hard to acquire, since they
fication presented below the first two categories (in involve administering a known dose of a pathogen to a
which no latency is observed) are separated from the volunteer. Information is scanty and is generally con-
remaining categories (in which a definite latent period cerned with doses required to infect, say, half those
occurs). exposed, rather than a minute proportion, at a single
Persistence, or survival, of the pathogen in the exposure. The volunteers have usually been well-nour-
environment is a measure of how quickly it dies after it ished adults from nonendemic areas. Such results have
has been passed in the feces. It is the single property to be applied with great caution (if, indeed, they can be
most indicative of the fecal hazard, in that a very applied at all) to malnourished children continuously
persistent pathogen will create a risk throughout most exposed to infection.
treatment processes and during the reuse of excreta. Host response is important in determining the result
A pathogen that persists outside the body only for a of an individual's receiving a given dose of an infectious
very short time needs to find a new susceptible host agent. In particular, acquired immunity and the rela-
rapidly. Hence, transmission cannot follow a long route tion of age to pathology are important for predicting the
through sewage works and the final effluent disposal effects of sanitation improvements. In general, the
site back to man, but rather will occur within the family balance between exposure to infection and a host's
by transfer from one member to another as a conse- response to it will determine the pattern of excreta-
quence of poor personal hygiene. More persistent or- related disease. If transmission creating exposure to a
ganisms can readily give rise to new cases of disease particular infection is low, then few people will have
farther afield, and, as survival increases, so also must encountered the infection and most will be susceptible.
concern for the ultimate disposal of the excreta. If a sudden increase in transmission of the disease
Though it is easy to measure persistence or viability occurs, it will affect all age groups in epidemic form.
of pathogenic organisms by laboratory methods, to Improvements in sanitation will have a significant
interpret such results it is necessary to know how many effect under these circumstances by reducing the likeli-
pathogens are being shed in the excreta (which is hood of an epidemic and, should one ever occur, its
relatively easy to determine) and the infective doses for magnitude.
man (which is extremely difficult to discover). By contrast, if transmission is very high the popula-
Under some conditions, certain pathogens will multi- tion will be repeatedly exposed to an infection and first
ply in the environment. Originally low numbers can be acquire it in childhood. Subsequent exposures may be
multiplied to produce a potentially infective dose. without effect if long-lasting immunity is acquired
Multiplication can take the form of reproduction by from the first attack. Alternatively, immunity may be
bacteria in a favorable environment (for example, cumulative from a series of attacks. The infection will
Salmonella on food) or of the multiplication by trema- always be present and is described as endemic. Under
tode worms (the parasitic flatworms, including flukes) these conditions much transmission is ineffective be-
in their molluscan intermediate hosts. cause of human acquired immunity, and reduced trans-
70 ANALYSIS OF FIELD STUDY RESULTS
mission as a result of improved sanitation will only environmental classification presented below distin-
delay the date of infection until later in life. Large guishes six categories of excreted pathogens (see also
sanitary improvements will either render the infection table 4-2).
rare or, if the disease was originally highly transmitted,
make it an adult disease. Examples are typhoid, which Category I
can be completely prevented in the community by
cadequae ompletlympented in excrethe andofmsupplies, These are the infections that have a low infective dose
adequate management of excreta and of water (s0)unpwoepahoeslriifctveimditl
and poliomyelitis virus infection, which requires ex- (< IO') and whose pathogens are infective immediately
treme hygienic precautions to prevent. In practice, on excretion. These infections are spread very easily
improved sanitation increases the disease problem by from person to person wherever personal and domestic
deferring infection to an age where its clinical course is hygiene are low. Therefore, it is likely that changes in
more severe. excreta disposal technology will have little, if any,
Consequences of a juvenile age-prevalence are that effect on the incidence of these infections if the changes
not only do children suffer chiefly from the diseases, but are unaccompanied by sweeping changes in hygiene,
also that they are the main sources of infection, so that which may well require major improvements in water
the most important need for better community excret'a supply and housing, as well as major efforts in health
disposal is among young children, the group perhaps education. The most important aspect of excreta dis-
least inclined to use any facilities that may be available, posal for the control of these infections is the provision
Some excreted diseases are infections exclusively or of a hygienic toilet (of any kind) in the home so that
almost exclusively of man, but many involve other people have somewhere to deposit their excreta. What
animals either as alternatives to man as host or as hosts subsequently happens to the excreta (that is, the means
of other stages in the life cycle. In the case in which wild of transport, treatment, and reuse) is of less importance
or domestic vertebrate animals act as alternative hosts, because most transmission will occur in the home.
control of human excreta is not likely to achieve Although transmission can, and does, occur by complex
complete prevention of the infection. Alternatively, if routes, most transmission is directly person to person,
the infection under consideration needs an animal host and therefore the provision of hygienic toilets alone will
for some intermediate stage, but also requires man, have a negligible effect. However, categories I and II
then the control of human excreta can be very effective merge into each other and form a continuum (see
in controlling the disease. Some excreted helminthic below).
infections that have intermediate aquatic hosts fall into
this category. These will be controlled if: excreta are Category 11
prevented from reaching the intermediate host; or the The infections in this category are all bacterial. They
intermediate hosts are controlled; or people do not eat have medium or high infective doses (> I lO) and so are
the intermediate host uncooked or do not have contact less likely than category I infections to be transmitted
with the water in which the intermediate host lives by direct person-to-person contact. Their bacteria are
(depending on the particular life cycle). persistent and can multiply, so that even the small
numbers remaining a few weeks after excretion can, if
they find a suitable substrate (such as food), multiply to
Environmental Classification form an infective dose. Person-to-person routes are
of Excreted Infections important, but so are other routes with longer environ-
mental cycles, such as the contamination of water
The list of human pathogens in excreta given in table sources or crops with fecal material.
4-1 is useful only insofar as it shows that the variety of The control measures listed under category I are
pathogens is wide and that they are members of one of important-namely water supply, housing, health edu-
four groups of organisms: viruses, bacteria, protozoa, cation, and the provision of hygienic latrines-but so
and helminths. It is essentially a biological classifica- are waste treatment and reuse practices. Changes in
tion. To the sanitation program planner it is interesting, excreta disposal and treatment practices alone may
but not very helpful. An environmental classification reduce the incidence of some infections such as cholera
that groups excreted pathogens according to common and typhoid but are unlikely to be as effective against
transmission characteristics is much more helpful in enteroviral infections, salmonelloses (other than
predicting the health effects of sanitation improve- typhoid), and infections from Shigella sonnei, Giardia
ments and in understanding the health aspects of lamblia, Enterobius vermicularis, and enteropatho-
excreta and sewage treatment and reuse processes. The genic Escherichia coli (these last pathogens are still
PUBLIC HEALTH ASPECTS 71
Table 4-1. Excreted Infections
Biological group and organism Diseasea Reservoire
Viruses
Coxsackievirus Various Man
Echovirus Various Man
Hepatitis A virus Infectious hepatitis Man
Poliovirus Poliomyelitis Man
Rotavirus Gastroenteritis in children ?
Bacteria
Campylobacter species Diarrhea in children Animals and man
Pathogenic Escherichia coli Gastroenteritis Man
Salmonella typhi Typhoid fever Man
S. paratyphi Paratyphoid fever Man
Other salmonellae Food poisoning Man and animals
Shigella species Bacillary dysentery Man
Vibrio cholerae Cholera Man
Other vibrios Diarrhea Man
Yersinia species Yersiniosis Animals and man
Protozoa
Balantidium coli Mild diarrhea Man and animals
Entamoeba histolytica Amebic dysentery and liver abscess Man
Giardia lamblia Diarrhea and malabsorption Man
Helminths
Ancylostoma duodenale Hookworm infection Man-soil-man
Ascaris lumbricoides Ascariasis Man-soil-man
Clonorchis sinensis Clonorchiasis Animal or man-*snail-fish---man
Diphyllobothrium latum Diphyllobothriasis Animal or man-copepod--*fish-man
Enterobius vermicularis Enterobiasis Man-*man
Fasciola hepatica Fascioliasis Sheep-*snail-aquatic vegetation-man
Fasciolopsis buski Fasciolopsiasis Pig or man->snail-aquatic vegetation-man
Gastrodiscoides hominis Gastrodiscoidiasis Pig-*snail---aquatic vegetation-man
Heterophyes species Heterophyiasis Dog or cat->snail-fish--*man
Hymenolepis species Hymenolepiasis Man or rodent-man
Metagonimus yokogawai Metagonimiasis Dog or cat--snail--*fish-->man
Necator americanus Hookworm infection Man-.soil-man
Opisthorchis felineus Opisthorchiasis Animal-*snail-*fish-man
0. viverrini Opisthorchiasis Animal--.snail---fish-man
Paragonimus westermani Paragonimiasis Animal or man-snail--*crayfish--man
Schistosoma haematobium Schistosomiasis Animal or man-*snail-man
S. mansoni Schistosomiasis Man-*snail--->man
S. japonicum Schistosomiasis Man-snail-man
Strongyloides stercoralis Strongyloidiasis Man or dog(?)-man
Taenia saginata Taeniasis Man--.cow-*man
T. solium Taeniasis Man-*pig--man. or man--man
Trichuris trichiura Trichuriasis Man-soil-man
? Uncertain.
a. With all diseases listed, a symptomless human carrier state exists.
b. For helminths, the transmission process is given.
Source: Richard G. Feachem and others, Sanitation and Disease: Health Aspects of Excreta and Wastewater Management. World
Bank Studies in Water Supply and Sanitation no. 3 (Baltimore: Johns Hopkins University Press, forthcoming).
commonly transmitted within affluent communities in fragile will clearly tend to be spread in an intrafamilial
industrialized countries). or other close pattern and depend for its control more on
The criteria chosen to separate categories I and II are personal hygiene and less on sanitation. A low infective
infective dose and "length" of the environmental cycle, dose, however, in an environmentally persistent organ-
since the aim is to predict the efficacy of sanitation ism will lead to an infection very difficult to control
improvements as a control measure. The reason they do either by sanitation or by personal and domestic hy-
not form tidy groups is the variable persistence of the giene. Many viruses fall into this category and pose
pathogens involved. The extreme category-I pathogen major problems of control. For them, induced immu-
that has a low infective dose and is environmentally nity may be the best approach, as discussed above for
72 ANALYSIS OF FIELD STUDY RESULTS
Table 4-2. Environmental Classification of Excreted Infections
Category and epidemiological Environmental
feature Disease transmission focus Major control measure
1. Nonlatent; low Amebiasis Personal Domestic water supply
infective dose Balantidiasis Domestic Health education
Enterobiasis Improved housing
Enteroviral infection, Provision of toilets
Giardiasis
Hymenolepiasis
Infectious hepatitis
Rotaviral infection
t. Nonlatent; medium Campylobacter Personal Domestic water supply
or high infective infection Domestic Health education
dose; moderately Cholera Water Improved housing
persistent; able Pathogenic Crops Provision of toilets
to multiply Escherichia Treatment of exereta
coli infection before discharge or reuse
Salmonellosis
Shigellosis
Typhoid
Yersiniosis
In. Latent and persistent; Ascariasis Yard Provision of toilets
no intermediate host Hookworm infectionh Field Treatment of excreta
Strongyloidiasis Crops before land application
Trichuriasis
iv. Latent and persistent; Taeniasis Yard Provision of toilets
cow or pig as Field Treatment of excreta
intermediate host Fodder before land application
Cooking. meat inspection
v. Latent and persistent; Clonorchiasis Water Provision of toilets
aquatic intermediate Diphyllobothriasis Treatment of excreta
host(s) Fascioliasis before discharge
Fasciolopsiasis Control of animal
Gastrodiscoidiasis reservoirs
Heterophyiasis Cooking
Metagonimiasis
Paragonimiasis
Schistosomiasis
vt. Excreta-related Bancroftian filariasis Various fecally Identification and
insect vectors (transmitted by C(ulex pipiens) contaminated sites in elimination of suitable
and all infections in which insects breed insect breeding sites
i-v for which flies and
cockroaches can be vectors'
Source: Feachem and others, Sanitation and Disease.
a. Includes polio-, echo-, and coxsackieviral infections: poliomyelitis; viral meningitis; diarrheal, respiratory, and other diseases (see
Feachem and others, chapter 1).
b. Ancylostoma duodenale and Necator americanus.
c. Culex pipiens is a complex of mosquito species and subspecies. The principal tropical species, and the vector of filariasis in those
tropical areas where the infection is transmitted by Culex. is Culex quinquefasciatus (previously also known as Culex pipiens fatigans,
C. p. quinquefasciatus, or C. fatigans).
poliomyelitis. For category ii, sanitation improvements hygiene because the helminth eggs are not immediately
reduce the efficacy of the longer cycles and thus have a infective to man. Domestic hygiene is relevant only
greater overall benefit than for category I pathogens insofar as food preparation must be adequate to destroy
(for which these longer cycles are of little significance). any infective stages present on food, and latrines must
Category III be maintained in a tolerable state so that eggs do not
remain on the surroundings for the days or weeks of
This category contains the soil-transmitted hel- their latent period. If ova are not deposited on soil or
minths. They are both latent and persistent. Their other suitable sites for their development, transmission
transmission has little or nothing to do with personal will not occur. Therefore, any kind of latrine that
PUBLIC HEALTH ASPECTS 73
contains or removes excreta and does not permit the Category VI
contamination of the floor, yard, or fields will limit This category is reserved for excreted infections that
transmission. Because persistence of ova is so long, are, or can be, spread by excreta-related insect vectors.
however, it is not sufficient to stop fresh feces from The or tant ad by tese vectors
reaching the yard or fields. Any fecal product that has The most important and ubiquitous of these vectors are
not eenadeuatly reaed ustnotreah te sil, mosquitoes, flies, and cockroaches. Among the mosqui-
not been adequately treated muse t rea o the toes there is one cosmopolitan group, Culex pipiens,
Tberefore, in societies thatreustheirexcretaonthe that preferentially breeds in highly contaminated water
land, effective treatment (for example, storage of ex- and is medically important as a vector of the worms that
creta for at least a year) is vital prior to reuse. auS filarai Impothanttws aroupor ofith wormsotha
cause filariasis. The other two groups, flies and cock-
roaches, proliferate wherever feces are exposed. Both
Category IV have been shown to carry large numbers and a wide
This category contains only Taenia saginata and T. variety of excreted pathogens on their feet and in their
solium, the beef and porktapeworms, respectively. Any intestinal tracts, but their importance in actually
system that prevents untreated excreta from being spreading disease from person to person is, in fact,
eaten by cattle and pigs will control transmission of controversial (though their nuisance value is great).
these infections. Cattle are likely to be infected in fields Flies have also been implicated in the spread of eye
treated with sewage sludge or effluent. They may also infections and skin lesions.
eat feces deposited in cowsheds. Pigs are likely to The implicit control measure is to prevent access of
become infected eating human feces deposited near the the insects to excreta, and this can be achieved by many
home or in the pigsty. sanitation improvements of differing sophistication. In
Therefore, the provision of toilets of any kind to general, the simpler the facility, the more care is needed
which cattle and pigs do not have access, and the to maintain it insect-free. Cockroaches, flies, and Cu-
treatment of all wastes prior to land application, are the lex mosquitoes have numerous breeding places other
necessary control methods. It is also necessary to than those connected with excreta disposal and, thus,
prevent birds, especially gulls, from feeding on trickling can never be controlled by sanitation improvements
filters and sludge drying beds and subsequently depos- alone.
iting the tapeworm ova in their droppings on pastures.
Personal and domestic cleanliness are irrelevant as long Health Effects of Treatment
as toilets are used. and Reclamation
C.ategory V
Category V As described above, some of the infections in cate-
These are the water-based helminths, which need an gories Il-V require for their control proper treatment
aquatic host or hosts to complete their life cycles. before disposal or reclamation. Waste treatment tech-
Control is achieved by preventing untreated night soil nologies for developing countries depend upon the
or sewage from reaching water in which the intermedi- level of water service and the kind of sanitation sys-
ate hosts live. Thus, any land application system or any tem involved. The health aspects of three treatment
dry composting system will reduce transmission. There options-stabilization ponds for waterborne wastes,
are two complications. First, in all cases (except Schis- night-soil digestion with or without methane (biogas)
tosoma mansoni and S. haematobium), animals are an recovery, and composting-may be evaluated accord-
important reservoir of infection. Therefore, any control ing to the time-temperature relations that achieve the
measures restricted to human excreta can have only a death of excreta-related pathogens.
partial effect. Second, in the case of S. haematobium, it Minimal times and temperatures that will ensure
is the disposal of urine that is of importance, and this is pathogen death are shown in figure 4-1. The most
far more difficult to control than the disposal of feces. resistant pathogens are enteric viruses and Ascaris
Because multiplication takes place in the intermediate eggs; by the time these are killed, all the others have
hosts (except in the case of the fish tapeworm, Diphyl- died. The curve for Ascaris eggs is based upon a large
lobothrium latum), one egg can give rise to many body of data; that for the viruses is less certain. In any
infective larvae. A thousandfold multiplication is not event, the typical temperatures reached during aerobic
uncommon. Therefore, effective transmission may be composting by the Beltsville Agricultural Research
maintained at low contamination levels, and the re- Center (BARC) process described in chapter 2 are more
quirements of adequate excreta disposal relative to the than enough to destroy all known pathogens.4
percentage of all feces reaching the toilet are very Figure 4-1 also indicates that anaerobic night-soil or
exacting. sludge digestion-at the ambient or slightly raised
74 ANALYSIS OF FIELD STUDY RESULTS
Figure 4-1. Influence of Time and Temperature on Selected Pathogens
in Night Soil and Sludge
70 - 70
Enteric
viruses
65 - 65
Shigella
60 Safety zone -60
55 Taenia \ ^< \5
55 55
50 - 5
Vibrio cholerae
45 -.--------45
40 Ascaris 40
Salmonella
35 _ 35
N:Z
30 _ 30
25 : Entamoeba 25
1 histolvtica
20 l l 20
0.1 1 10 100 I1,000 Ii0.000
1 day 1 week 1 month 1 year
Time (hours)
Note: The lines represent conservative upper boundaries for pathogen death-that is. estimates of the
time-temperature combinations required for pathogen inactivation. A treatment process with time-temperature
effects falling within the "safety zone" should be lethal to all excreted pathogens (with the possible exception
of hepatitis A virus-not included in the enteric viruses in the figure-at short retention times). Indicated
time-temperature requirements are at least: 1 hour at �621C. I day at �500C. and 1 week at a460C.
Source: Richard G. Feachem and others, Sanitation and Disease: Health Aspects of Excreta and Wastewater
Management, World Bank Studies in Water Supply and Sanitation, no. 3 (Baltimore: Johns Hopkins
University Press, forthcoming).
PUBLIC HEALTH ASPECTS 75
temperatures found in night-soil storage pits or vaults Other reports of possible infection due to aerosols from
(say, up to 35�C in tropical areas) for detention periods spray irrigation in Israel, and to ridge and furrow
of twenty to thirty days-will substantially reduce but irrigation of crops with poorly treated sewage in a
not eliminate Ascaris eggs in the sludge.5 For digesters number of places, reaffirm the need for careful selec-
heated to 45 or 50 �C, complete destruction will occur. tion and operation of waste treatment facilities that will
Storage in a well-drained pit for one year will also adequately protect nonimmune human populations."
suffice for an essentially complete kill; the same is true Where excreta are fed to fish or pigs-as in South and
for excreta in a pit privy or a composting latrine. Southeast Asia, West Africa, and Central Ameri-
If pathogens are not removed by prior treatment, ca-waste treatment should be complemented by care-
they can survive on soil as follows: ful cooking of the meat. Methane from a household
months Survival time biogas unit or a community digester has no hazard of
Viruses <6 months, but generally <3 months infection, but the sludge or slurry will require the same
Bacteria < 3 years, but generally <2 months treatment as that for night soil or sewage treatment
Protozoa < 10 days, but generally <2 days plant sludge.
Helminths < 7 years, but generally <2 years Risks of infection from eating foods grown with
water or fertilizer from raw or treated sewage, sludge,
Survival of excreted pathogens on crop surfaces may feces, or urine depend upon the kind of crop and
be as follows:6 whether it is eaten raw, upon handling of the food
Survival time before and after cooking, and upon the time-tempera-
Viruses MM< 2 months, butgenerally <I month ture factors-in the interior of the food during cooking.
Bacteria MM <6 months, but generally <I month No attempt is made here to generalize on effects of
Protozoa M<5 days, but generally <2 days different methods of preparing and cooking contami-
Helminths MM5 months, but generally < I month nated foods. Eating raw or partially cooked pork or
Stabilization ponds can provide adequate low-cost whole fish from animals fed on feces is clearly not safe.
.. Nor is eating unsterilized watercress or other raw
treatment for sewage. They are particularly effective in g
warm climates where a series of five to seven ponds plants grown in contaminated water. If the meat, fish,
each with a.rte, w mos or plant is cooked to the "well-done" stage, however,
heawinths and pretentizonatime ofrfivedays will rema a and no further contamination occurs during subsequent
helminths and protozoa and reduce the concentrations food handling, there will be no risk. The matter is a
of other enteric organisms to levels safe for irrigation, clua handl ted iol oe wors ifecer on t
Health hazards of night-soil and sewage-reclamation cultural and educational one whose influence on the
systems have been well documented. The reclamation design and operation of waste reclamation systems
systems considered here include methane production at must be determined on a case-by-case basis.
household and community levels, irrigation of gardens
or crops, fertilization of fields or ponds for agriculture Conclusion
or aquaculture, and pig feeding. Areas of potential
health hazard include exposure of the workers and Sanitation improvements are necessary but, in them-
contamination of foods, selves, are not sufficient for the control of excreted
Data on the health effects of night soil or sewage infections. Nevertheless, without them, excreted infec-
upon sanitation or agricultural workers are inconclu- tions can never be controlled. Other complementary
sive, although the risk is self-evident. Although there is inputs, such as improved water supplies and sustained
unquestionably a hazard, most surveys made to date health education programs, are essential for success.
reveal no greater susceptibility to disease than that of The theoretical, potential health benefits from environ-
the general population in industrial countries.8 An mental sanitation improvements alone and from
exception is a 1971 survey in India of workers on farms personal hygiene improvements alone are summarized
fertilized with raw sewage that reported significantly in table 4-3. The outstanding difference in the table is
higher levels of intestinal parasites, anemia, skin disor- between categories I and 11 together, which depend so
ders, and diseases of the respiratory and intestinal strongly on personal and domestic hygiene, and the
tracts.9 other categories, which do not. Category-I and -ii
Risk to the general population is better known. infections are thus much more likely to be controlled if
Recent developments in China include night-soil treat- 20-40 liters per capita daily of safe water are made
ment, along with snail eradication programs prior to available concurrently with sanitation improvements
use of night soil as fertilizer, to reduce prevalence of and if an effective and sustained program of health
schistosomiasis and concurrently to reduce ascariasis.'� education is organized.
76 ANALYSIS OF FIELD STUDY RESULTS
Table 4-3. Potential Health Improvements
Potential improvements from
Category Sanitation Personal hygiene
of infection alone alone Other control measures
I Negligible Great None
ut Slight-Moderate Moderate Proper waste treatment
III Great Negligible Proper waste treatment
IV Great Negligible Proper waste treatment
v Moderate Negligible Proper waste treatment.
animal control, or cooking of meat
VI Slight-Moderate Negligible Insect control
If one considers the changes necessary to control Management, World Bank Studies in Water Supply and Sanitation,
categories iii and iv, they are relatively straightfor- no. 3 (Baltimore: Johns Hopkins University Press, forthcoming).
ward: the provision of toilets that people of all ages will 2. For a more complete discussion of this topic, see chapter 5 in
use and keep clean and the effective treatment of Richard G. Feachem and others, Water, Wastes, and Health in Hot
excreta and sewage prior to discharge or reuse. The Climates (Chichester: John Wiley and Sons, 1977).
reason that the literature on the effects of latrine 3. Feachem and others, Sanitation and Disease.
4. Hillel 1. Shuval, Charles G. Gunnerson, and DeAnne S. Julius,
programs often does not show a marked decrease in the Appropriate Technology for Waler Supply and Sanitation, vol. IO,
incidence of infections in categories Ili through Vl is Night-soil Composting (Washington, D.C.: The World Bank, 1980).
because, although latrines were built, they were typi- 5. M. G. McGarry and J. Stainforth (eds.), Compost, Fertilizer,
cally not kept clean and often were not used at all by and Biogas Production from Human and Farm Wastes in the
children or by adults working in the fields. People's Republic of China, Publication no. IDRC-TS8e (Ottawa:
This points to the importance of supplementing International Development Research Centre, 1978).
sanitation improvement projects with health education 6. Suggested criteria for reduction of the health risks associated
with the agricultural reuse of excreta and sewage are presented in
and training programs for users. Operational research Feachem and others, Sanitation and Disease, and in standard works
is needed to develop effective ways of communicating on irrigation.
simple hygiene habits and motivating users to adopt 7. Ibid.
them. In addition, more information is needed on the 8. Ibid. See also C. Scott Clark and others, "Disease Risks of
destruction of pathogens in simple night-soil treatment Occupational Exposure to Sewage," Journal of the Environmental
systems, on viral survival in waste stabilization ponds, Engineering Division, Proceedings ofthe American Society of Civil
on the risks of groundwater pollution from on-site Engineers, vol. 102, no. EE2 (1976), pp. 375-88; and W. Anders,
"The Berlin Sewer Workers," Zeitschrift fir Hygiene, vol. I (1954),
sanitation systems, on the health hazards of various pp. 341-71.
methods of sullage disposal, and on methods of elimi- 9. Central Public Health Engineering Research Institute, Health
nating breeding of Culex pipiens in wet pit latrines. Status of Sewage Farm Workers, Technical Digest no. 17 (Nagpur,
India, 1971).
10. McGarry and Stainforth, Compost, Fertilizer, and Biogas;
Notes to Chapter 4 and M. G. McGarry, "Developing Country Sanitation," Report to
International Development Research Centre (Ottawa, February
1975).
1. Much of this chapter is taken from the volume issuing from the I1. Hillel 1. Shuval, "The Uses of Wastewater for Irrigation,
Ross Institute's study. For a complete account of the Institute's work with Special Reference to Enteric Pathogenic Protozoans and Hel-
and its bibliographic base, see Richard G. Feachem and others, minths," Proceedings ofthe Conference on Sanitation in Developing
Sanitation and Disease: Health Aspects of Excreta and Wastewater Countries, Oxford, England, July 1977.
5
Sociocultural Factors
NEARLY ALL STUDIES addressing the sanitation prob- a relation between environmental sanitation and good
lems of the rural and urban poor in developing countries health? Did they view environmental sanitation as a
affirm the importance of social and cultural factors in problem at all? If they did, why was it a problem and
the choice of appropriate technology. The operational how important was it in relation to other perceived
recommendation generally made is to increase commu- problems?
nity motivation and participation in the planning and Second, the survey investigated existing practices
selection stages in hopes that community responsibility related to water use and excreta disposal and prefer-
can be generated to use and sustain the system during ences for improvements. What were the problems
the operating and maintenance stages. The widespread associated with obtaining water? What level of service
failure of community water supply and latrine pro- would be desirable and what was acceptable? What
grams, when measured by long-term successful opera- constraints were perceived in obtaining the desired
tion or usage, points to the need for a more careful improvements?
analysis of the sociocultural aspects of the choice of The survey also sought to identify incentives for
technology and for more specific operational guide- change. Were the people aware of alternative sources of
lines. water supply and methods of excreta disposal? What
This chapter summarizes the results of sociocultural were the perceived costs and benefits of the alterna-
surveys and case studies of social factors affecting the tives? Would community members be willing to collab-
selection of sanitation technology that were carried out orate with neighbors or contribute money, time, or
as part of the World Bank research project that pre- effort to improve their existing water supply and
ceded this volume.' These detailed case studies were sanitation facilities?
limited to Latin America; thus, their results must be To supplement the survey, the researchers used
interpreted with caution by those working in other parts various anthropological techniques in the Latin Ameri-
of the world. Many of the Latin American findings can field studies, including direct observation of water-
were supported by surveys conducted in Asian and carrying tasks and water reuse practices, indirect ob-
African communities, but constraints of time prevented servation of personal hygiene and habits of latrine use,
verification of these surveys through additional case interviews with local leaders and individuals involved in
studies. sanitation programs, and informal conversations with
local storeowners and craftsmen. One of the method-
The questionnaire used in all communities was de- ological conclusions from the case studies was that,
signed to provide community input during the design without these "unstructured" information-gathering
stage of project implementation; it generally followed techniques to supplement the formal surveys, the re-
the form used by White, Bradley, and White in East sponses obtained in the latter were often misleading or
Africa.2 Such a questionnaire is one of the behavioral so incomplete as to be useless for guiding project design.
scientist's tools for carrying out stage 1 in figure 1-1. Its In addition to community-based data collection,
purpose was to find out what community members pertinent information was assembled on the national
thought about their present methods of water supply and regional organizations involved in community wa-
and excreta disposal and how they would respond to an ter supply and waste disposal improvement. Both the
opportunity to change those methods. successful and unsuccessful components of present and
The survey first attempted to determine how people past programs were examined. This information on
perceived their environment. Did they think of it as a institutional issues has been incorporated in the pro-
healthy place to live? What were their criteria for gram recommendations presented in chapter 7 of this
evaluating a good or healthy environment? Did they see appraisal.
77
78 ANALYSIS OF FIELD STUDY RESULTS
often accompany many households' sharing the same
Survey Results public tap. In many cases, the opportunity for socializ-
Although each of the case studies provided many ing while drawing water or washing clothes is not
useful and original insights, the generalizations pre- considered a benefit and may even have a negative
sented below represent the central and pervasive find- value.
ings on environmental sanitation. These findings can In communities where public taps have been intro-
also provide planners with some indication of the kind duced, most households desire greater accessibility
and quality of information that can be collected through the installation of more taps at shorter dis-
through a survey given before a project's initiation. tances or through the provision of private connections.
Where public taps are close and a private connection
Perceptions involves additional cost, many prefer, as a cheaper
If the majority of a population perceives their envi- alternative, the use of a hose to fill large drums placed
ronment to be healthy, it is for reasons unrelated to next to the house.
sanitation. Many people believe their environment is An aesthetically attractive facility for excreta dis-
healthy because it provides fresh and good air, good posal, with a shiny porcelain seat or a brightly painted
climate, or accessibility (for example, is "close to the cement floor, is preferred over cheaper, less attractive
highway in case anything goes wrong"). In crowded, alternatives. Although people use a squatting position
concentrated settlements, a healthy environment is when defecating in the fields in Latin America, they
viewed as one that allows for privacy and is character- prefer a latrine with a seat.
ized by good relations with one's neighbors. Signifi- Where lack of space or rocky soil are constraints for
cantly, all of the reasons cited above are based on the installation of household latrines, there is an ex-
respondents' observations of their immediate surround- pressed and sometimes observed willingness to use a
ings. A healthy environment is certainly not associated, public facility or to share one with neighbors. People
in residents' perceptions, with abstract theories on usually share latrines only with close friends, relatives,
disease vectors or with contamination through contact or good neighbors. Where sanitary facilities are main-
with nonvisible pathogens in water or wastes, tained by attendants, however, the demand for use of
wlth~ ~ ~ ~~~~~~~~~~~~bi facilities ishoen hi h.e rwats
In contrast, those who perceive their environment as public facilities is high
unhealthy most frequently cite reasons related to poor Once a latrine is filled, many households continue to
sanitation. Individuals in this category are a small use the superstructure by transferring it to a new site.
minority in rural communities and a significant major- Most people, however, perceive a need for technical
ity only in some urban fringe communities. Again, assistance when initially installing latrines, and without
visible contaminants-such as dead animals in the continuous or at least periodic promotion-even in
water source-are often included in explanations of communities where initial acceptance is high-new
why a water source was "bad." Most believe water families do not usually take the initiative to install a
quality is good if the water looks clean. Color, taste, and latrine.
smell are important criteria. Where improved supplies
exist, the water may be considered of good quality Incentives
because it is piped or introduced by a government People can be successfully motivated to install ex-
health institution. creta disposal facilities by: a desire to acquire the
An understanding of the relation between water and benefits of another service, such as a health clinic or an
health may occur when consumers are suddenly de- improved water supply; population pressures causing
prived of their utilities after an extended period of use. crowding and an increased need for privacy; interest in
When their piped water system broke down and they acquiring "modern" conveniences in the village or what
were forced to use an unprotected well once again, the are regarded as status symbols (either by definition of
women of one Mexican village observed an increase in the village leaders or by the awareness of models from
diarrhea among themselves and their children, and they more developed countries created by the tourist indus-
attributed this to the change in water source. try); and social pressures to comply with a collective
village decision arrived at through a consensus of
leaders and household heads.
Abundance and proximity are the two primary quali- In almost all of the communities studied, the people
ties appreciated in a water supply. Two of the most offer some suggestions for improving the existing water
objectionable factors associated with an improved wa- supplies or sanitation facilities (or both). Though lack
ter supply are cost (if the water is paid for) and the of economic resources is often given as a reason for not
crowding, quarrels, and problems with neighbors that having implemented ideas for improvement, lack of
SOCIOCULTURAL FACTORS 79
leadership and lack of technical knowledge are cited primarily in individual households. Defecation in corn-
almost as frequently in some communities and more fields or on coffee plants is considered to serve a
often in others. People are more willing to give time in fertilizing function. Similarly, fruit trees are purposely
working to improve their sanitation facilities than to planted over old, filled latrine pits. In some areas,
pay more than a very small amount of cash for improve- human excreta deposited near the house are consumed
ments. Those unwilling to collaborate with others to by pigs. This last practice is sometimes formalized,
improve water supplies are a small minority and cite as when penned pigs are released periodically to clean
their reasons previous bad experiences, poverty, or that areas that have been designated and used for the
the present supply is good or close enough for their depositing of human waste. Native pigs are sometimes
needs. even preferred over new breeds because they carry out
this important function and can be fed corn and scraps
Motivation instead of commercial concentrates. Behavioral pat-
terns incorporating excreta reuse as a principle can
The need for different or improved excreta disposal provide the basis for uneducated people to understand
facilities is rarely given priority except when the com- composting and biogas when these new technologies are
munity has become crowded, housing is concentrated, adequately explained.
and the lack of privacy has become a problem. As a When there exists a credibility gap between external
result of being linked with a need perceived to be of agencies and communities because of past community
higher priority-such as health services, water supply experiences with abortive attempts to introduce innova-
improvements, or income-generating projects intro- tions or compulsory programs, people are less willing to
duced through integrated community development pro- collaborate until materials or technical assistance are
grams-the installation of latrines or other means Of actually seen or made available. When communities
excreta disposal can receive substantial community are legally authorized to keep the fund for water supply
support and acceptance. In marginal squatter commu- maintenance in the community, or when economic
nities, a major constraint to investing in improved resources for sanitation are made available through
sanitation is the fear of eviction. income-generating projects, local people take the initia-
Community values of unity and progress may be tive in defining as well as solving their own problems,
considered more important benefits than cleanliness and popular participation is more pervasive.
and sanitation in communally approved projects for the
installation of excreta disposal facilities. The costs (in
money and time) of installing a latrine may be per- Behavioral Science and Sanitation
ceived as minor when compared with the costs (in social Project Design
pressure, loss of good will, and deterioration of solidar-
ity) of not installing one. These highly specific findings from structured sur-
The extent of community involvement in environ- veys are only a start in providing planners with an
mental sanitation projects is directly related to op- understanding of the social factors that influence the
portunities for frequent contact and the exchange thinking that will determine whether potential users
of information with technically informed individuals. will accept, properly use, and maintain the services
When the facilitators or promoters presenting a project provided. A limitation of the use of questionnaires is the
are socially and culturally similar to the population high cost in time and trained personnel needed to
with whom they are working, communication is more analyze a survey administered in every community to
effective. be served. The objective of incorporating the techniques
A general philosophy that nothing should be wasted of social science should not be to provide a few with
was evident in most of the communities studied, custom-made latrines, but to provide many with
particularly in the rural ones. Water from laundry is acceptable sanitary facilities they are willing to use and
stored for later use to settle dust and clean floors. Water maintain.
used to wash dishes, soak corn, or clean vegetables is Another problem with surveys is the difficulty of
saved and fed to chickens, pigs, and other small domes- obtaining reliable data on which to base decisions.
tic animals along with food crops. Reuse of human When asked if they would be willing to contribute to
excreta is an understood concept and is practiced projects, people must know how much, and of what,
traditionally in Latin America, albeit in a less advanced they are being asked to contribute. People are reluctant
and systematic way than in Asia. Reuse is informal to respond when given a choice expressed in a hypothet-
-often not spoken about because of the sociocultural ical manner. Yet, when the technology suggested for a
taboo surrounding the subject-and it takes place community is new to them, it is hard to pose concrete
80 ANALYSIS OF FIELD STUDY RESULTS
questions that will be meaningful.
A survey preceding a proposed project also risks
unintentionally misleading respondents into believing Figure 5-1. The Sociocultural Dimension
that an effort is being made to solve their particular and of Sanitation Project Design:
immediate sanitation problems. Raising false expecta- Contributions of Social Science
tions has contributed greatly to the credibility gap that
exists between communities and outsiders. People's
past experiences with unfulfilled promises have created
in them an unwillingness to become involved in self- Design of technology:
help projects unless they can actually see materials or a researci of selected area.
similar demonstration of commitment on the part of
agencies offering them assistance.
The limitations of surveys in predicting users' prefer- The innovation:
ences and willingness to pay have important implica- * is technically feasible
tions for planning. The case studies suggested that 0 is cost efficient
* can be understood bv users
surveys are most productive when complemented with 0 fulfills users' needs and
unstructured information-gathering techniques at par- expectations
ticular points in project design. 0 is affordable
There are three components of project design that * can be maintained by users
can be greatly strengthened by well-timed and -planned
inputs from the social sciences: selection of technology,
its diffusion, and its adoption. These major compo- Means for the dlffusion oftechnology:
nents, and the kind of input from social science recom- evaluation of existing
mended for each, are summarized in figure 5-1. The institu ons and programs
discussion below elaborates on the integration of the
inputs into these components of project design. Channels and systems exist for:
* responsive administration
Selection of technology * promotion of activities
and health education
Insights into the reactions of users must be found in 0 efficient deliverv
the study of communities in which technologies have of service
already been introduced and accepted (or rejected). S instruction on operation
already *~~~~~~~~~~~~~~~~~~ training in maintenance
The communities should be as culturally and environ- * effective delegation
mentally similar as possible to those in the area or of authoritv
region selected for sanitation improvement. Through a * periodic monitoring
preliminary analysis of agency records, researchers can
find out how much consumers have promised to con-
tribute and how much they are actually contributing to
maintenance of sanitation systems. The research will Motivation for the adoption orf technology-v
consultation and community. organuiatnon
indicate the willingness of future beneficiaries to sup-
port such maintenance through contributions of money
or time. The communities have input to:
On the basis of this preliminary research, technical * project initiation
and administrative packages can be developed for * design (choice of level of service,
communities environmentally and culturally similar to location, and the like)
those studied. In this way, when the range of alternative * scheduling labor-intensive
activities
technology is made available to consumers in the * instruction on operation
selected area, promoters can be as specific as possible * training in maintenance
about contributions and responsibilities expected of the 0 fee collection (frequency of and
community. mechanism for)
* authority to enforce sanctions
(for tardy fee payments. noncompliance
Meansfor the diffusion of technology in maintenance, and the like)
Because of the low priority given to sanitation needs
in many communities, planning at the national level
SOCIOCULTURAL FACTORS 81
should link the disposal of human waste with other tions, and other related health activities). For this
services given higher priority by the communities (for reason, promotion should continue on a periodic (cam-
example, water supply or health clinics). In the rural paigns by promoters) or continuous (campaigns by
areas, community involvement in planning water sup- radio) basis long after projects are initially constructed.
ply and sanitation projects usually requires the creation
of a branch office of the responsible agency that will be
accessible to consumers and that has decisionmaking M o
power for project selection and development in line with Because urban and concentrated rural settlements
the policies and priorities established by the agency's consider sanitation more of a problem than do dispersed
central office (see chapter 7). communities, initial efforts to introduce sanitation
For purposes of liaison with the community, the technologies are likely to be more effective in urban
agency responsible for water supply and sanitation than in rural areas. The existence of conflicting factions
should rely on facilitators or promoters assigned to an and the fear of eviction (in squatter communities) may,
existing local agency such as a health clinic. If this kind however, mean that monetary or labor contributions
of personnel does not exist, teachers or agricultural will be more difficult to obtain. In the rural areas,
extension workers should be requested to assist in sanitation can sometimes be linked with a request for an
technical tasks, community organization, and health improved water supply, which is more often the com-
education activities. The facilitators should be natives munity's priority. If the projects are implemented
of the region, they should have had experience working simultaneously, they will be viewed as related, and the
in the area, and they should share the cultural perspec- need for maintaining both will be clearer.
tives of the people with whom they will be working. An When the technology is understood by the popula-
effort should be made to recruit women as well as men tion, there is no need to build demonstration models to
so that information on improved hygiene practices promote it. If it is not understood, the use of slides or
related to water supply and sanitation can be more other visual media and visits to prototypes may be a
effectively communicated to local women and their more rapid means of gaining the support of community
children. The facilitators should receive intensive train- leaders than the building of demonstration models in
ing in the technical aspects of the technology and its each community. When adequate examples are not
promotion, and they should be provided with adequate available, however, demonstration models will usually
transportation and visual aid materials if they are be necessary. With any project, once the agency and the
responsible for promoting the technology in a number community have come to an agreement to undertake
of communities. the project, expected contributions and responsibilities
When an appropriate organizational structure does should be formally committed before its initiation.
not already exist at the community level, project partic- For the most efficient planning, communities should
ipants should be expected to organize a locally selected have some input into scheduling installation and con-
committee or cooperative to coordinate and oversee the struction activities according to seasonal migration
community's contributions to the project. The case patterns, planting and harvesting seasons, and climatic
studies suggest that such committees are capable of cycles. Decisions about the location of water distribu-
assuming a wide range of responsibilities when pro- tion outlets, colors for the sanitation facilities (if la-
vided proper authority and guidance. These responsi- trines are to be painted), when maintenance fees should
bilities can include providing liaison between the be collected (monthly, bimonthly, or by some other
agency and the community, organizing and maintain- schedule), and options for levels of service should be
ing records of the voluntary labor force, selecting allocated to consumers so that community initiative in
community members to be trained in facility mainte- decisions affecting the care and maintenance of the
nance, collecting the maintenance fee, keeping ac- facilities will be encouraged. Community leaders and
counting ledgers, and filing periodic reports to the project participants should also be encouraged to estab-
responsible authority concerning the results of these lish criteria by which individuals not participating in
activities. the original project may later be included.
When the promotion of a project at the community To ensure adequate maintenance of facilities, local
level is the responsibility of an individual or institution residents should be trained in simple procedures and in
involved in other activities, initial participation may be the reporting of major malfunctions to responsible
high. Continued promotion, however, often is not given authorities. Fees are more likely to be collected if they
because energies must be dedicated to competing activ- are maintained by an appropriately authorized commu-
ities that may also have the incentive of producing an nity organization, such as a "Water Supply Improve-
income (for example, selling medicines, giving injec- ment Committee." The local group should be required
82 ANALYSIS OF FIELD STUDY RESULTS
to maintain records and file periodic reports on its appropriate sanitation technology are crucial to its
collections and expenditures, and it should have author- successful introduction and diffusion.
ity to impose sanctions against those who fail in their Unfortunately, research into the design and delivery
committed payments. of these project components is scarce, and what is
A system for periodic project monitoring should be available tends to be extremely site specific. Perhaps
established. A monthly visit by the local sanitary this is a reflection of the nature of the inputs them-
inspector or some other authority from the responsible selves. Because these sociocultural components consti-
agency can be an effective motivational tool when it is tute the link between a technology and a particular
carried out in a culturally sensitive manner. Any community, it is obvious that they must be adapted to
problems that have arisen with use of the facilities can suit the local context. Yet, at the least, an analysis of
be discussed with local leaders in a nonthreatening which techniques of social science and which delivery
manner, and joint solutions can be negotiated. The methods have and have not been successful in the
visits will not only motivate communities to care for the implementation of sanitation projects needs to be at-
facilities, but they will also provide agencies with client tempted on a wider scale. If such an effort fails to reveal
contact and important feedback on changes in water any common characteristics of successful or unsuccess-
use and sanitation practices that have occurred after ful strategies, then a cumbersome and expensive site-
the introduction of new technologies. by-site approach, such as that used in this study, may
have to be adopted.
Conclusion
Many of these sociocultural aspects of the case Notes to Chapter 5
studies' findings seem self-evident. It was very difficult,
however, to find examples in the field of the widespread 1. For a more complete analysis of the sociocultural case study
diffusion of new technologies or of the sustained, results, see Mary Elmendorf and Patricia K. Buckles, Appropriate
successful operation of community water supply and Technology for Water Supply and Sanitation, vol. 5, Sociocultural
sanitation facilities. In some cases failures were from Aspects of Water Supply and Excreta Disposal (Washington, D. C.:
The World Bank, 1980). Much of this chapter is taken from that
poor technical design or the lack of institutional sup- work.
port. But, in many cases, the major problem was that 2. G.E. White, D.J. Bradley,andA. U. White,Drawersof Water:
the social and cultural factors discussed above had been Domestic Water Use in East Africa (Chicago: University of Chicago
ignored by planners. These "software" components of Press, 1972).
Part Two
Program Planning and Development
6
Implementation of Appropriate
Sanitation Technology
IN DESIGNING A PROGRAM for the implementation of were acquired and read, and 188 of them were chosen
appropriate sanitation technology, an important ques- for inclusion in the annotated bibliography. Thus, only
tion to answer is: why have inappropriate technologies about 1 percent of the published literature on waste-
been chosen in the past? This is really several questions water was found to relate to nonconventional sanitation
in one. Are alternatives to those technologies chosen technologies. The manual search yielded much better
available? If so, what is the appropriate procedure for results because it was directed toward those individuals
selecting among the alternatives? Given that selection and institutions known to have an interest in the
process, why has the result in the past been different subject. The final bibliography contained summaries of
from the one expected from what now appear to be 528 articles, of which nearly half were previously
more appropriate choices? Finally, how can those unpublished.' Efforts such as this can help bridge the
factors responsible for the difference be altered or information gap directly.
overcome to ensure that appropriate choices are made With few engineers aware of the range of sanitation
in the future? This chapter attempts to answer such technology available, it is not surprising that even fewer
questions as they relate to sanitation alternatives. planners and administrators know about the present
variety of technological alternatives. This lack of
knowledge has often meant that requests for sanitation
Obstacles studies have called only for the examination of different
configurations of sewerage systems. The least-cost
There are many points on the course toward evaluation has usually been limited to pipe sizes and
implementing an appropriate sanitation technology different treatment alternatives. Once a least-cost sew-
where the planner can encounter an obstacle and be erage system has been designed, its financial implica-
sidetracked. The first and most obvious problem found tions have been derived and compared with the city's
in the case studies, which form the basis of this analysis, capacity to raise funds. In most cases, this comparison
is the information gap. As described in chapter 2, many has led to a recommended staging of sewer construction
nonconventional sanitation technologies are being to serve downtown and wealthier residential areas
utilized around the world, but there is a real dearth of (often the only ones with piped water) in early years
detailed information on them. At the outset of this and to no recommended improvements for those living
study, the World Bank contracted the International in the rest of the city.
Development Research Centre (Ottawa, Canada) to Even if terms of reference have included the evalua-
carry out a detailed bibliographic search for informa- tion of nonconventional options, there have been biases
tion on sanitation technologies. They undertook their in the process of technology selection that have favored
investigation along two lines: through a rationalized sewerage systems. The background and training of the
computer search of a number of North American data bulk of consulting sanitary engineers certainly has
bases and through an ad hoc, manual search of selected constituted one bias. With very few exceptions, this
private and institutional libraries. The "key word" orientation is heavily directed toward sewerage
computer search produced about 18,000 titles, which modeled on systems in developed countries. Thus, most
were manually screened to obtain a short list of about sanitary engineers generally are good at designing a
700 articles that potentially included technical infor- workable sewerage system as one alternative, but they
mation useful to developing countries. These articles rarely have the knowledge or experience to "preselect"
85
86 PROGRAM PLANNING AND DEVELOPMENT
the best, and likely more appropriate, alternative tech- preferences in order to satisfy them at the least cost.
nology to compare with sewerage. If problems are Habits and ideas regarding human waste disposal are
encountered in designing a sewerage system to fit the highly variable across cultures and are not easily
site, they can usually devise ways to overcome them. discerned by the casual visitor. There are many exam-
But if problems arise in the design of an alternative ples in which cultural misunderstandings have led to
technology, it is often abandoned, rather than adapted, nonuse or misuse of new sanitation technologies. Fac-
because of the engineers' lack of design experience. tors such as the color or location of a latrine may have
Only time and increased exposure to nonconventional little technical import and yet be crucial to the accep-
solutions can overcome this difficulty. tance and use of a facility. In one new African commu-
Concurrently with the design of alternatives, the nity, an engineer designed the bathrooms to be in the
feasibility team prepares estimates of the demand for front of the houses so that the connection to the sewer
the service to be provided. This is another area in which would be as short as possible. The engineer did not
existing practice has favored sewerage. If economics is know, however, that people who were to use the facili-
"the dismal science" (as Thomas Carlyle called it in ties were unwilling to change their traditional practice
1849), engineering is the optimistic one. Linear de- of having the latrine in the back of the house, away from
mand projections made from tiny bases persist despite the view of passersby. Had this seemingly simple
historical evidence that, over the long run, demand consultation with users been made and their prefer-
growth is S-shaped and asymptotic. The supplies of ences determined before the sewers were laid, the
complementary inputs, such as piped water and addi- bathrooms could have been placed between the adjoin-
tional housing, have been assumed to be perfectly ing backyards of the houses at little additional cost. In
elastic. The influence of price on consumption has been this case, because the users had not been consulted
ignored. The intricacies of urban growth patterns have during the design process, by the time they discovered
rarely been explored, although they often are based the plans and complained about them the sewers were
upon an influx of population much poorer and less able already in place. Because the bathrooms then had to be
to afford service amenities than present populations. moved to the backs of the houses, the system that was
Thus, when historical rates of growth in demand have eventually built was far from the least-cost design.
been projected into the future, the lower consumption Even when demand analysis has been properly done
patterns of the new migrants are grossly overestimated. and consumers' preferences and financial constraints
Because sewerage master plans often cover periods of are known, it is possible to choose the wrong technology
more than twenty years, these errors have been com- by applying an inappropriate selection test. The most
pounded over time until a highly unrealistic picture of common fault has been the use of financial rather than
demand is created and used as the frame for testing economic costs in the least-cost analysis. The reasons
alternative technologies. The reason that the assump- why sewerage benefits from financial rather than
tion of rapid growth in demand has favored sewerage economic costing are that it is relatively capital inten-
over most nonconventional systems is that those tech- sive (and financial interest rates are generally below the
nologies with large economies of scale are more eco- opportunity cost of capital); it is relatively import
nomical under conditions of rapid growth. As pointed intensive (and foreign exchange is often officially
out in chapter 3, however, the financial consequences of undervalued); its cost to the householder in needed
investing in such large-scale technologies can be very plumbing and internal facilities is very high; it has
serious should demand turn out to be lower than relatively high water requirements (which are usually
projected. omitted from the cost comparison or included at a
There is one aspect of demand projection that de- market price below long-run production cost); and it
serves special emphasis because it has been ignored for possesses larger economies of scale than most noncon-
so long. This is the social, or micro-level, basis of any ventional systems for waste disposal that are not prop-
demand analysis. Behind any set of such numbers are erly valued where design populations are used for
the consumers whose individual needs and resources costing.
form the boundaries of consumption patterns. When
working in a familiar and homogeneous social environ-
ment, such as a Western European country, an engineer Incentives
incorporates social factors into the demand analysis
almost automatically because the engineer himself, Given the diversity of the obstacles to the selection of
generally, is a part of that same social fabric. But, in appropriate sanitation alternatives, a variety of incen-
developing countries, it is necessary for the engineer to tives or policy changes is likely needed if the conven-
make a real effort to discover the users' practices and tional practices of engineers and their clients in devel-
IMPLEMENTATION OF APPROPRIATE TECHNOLOGY 87
oping countries are to be revised. Some of these changes preparation of appropriate least-cost estimates for the
are obvious from the description of the problems. For various feasible alternatives has been discussed in
example, it is necessary to ensure that terms of refer- chapter 3. The behavioral scientist's work in eliminat-
ence for sanitation master plans include the examina- ing socially infeasible possibilities-and in acting as
tion of alternatives to sewerage. The international liaison between the community and the design engineer
lending agencies can have an important influence here in preparing the final project designs-is covered in
because they are often called upon to review terms of chapter 5. In addition, the behavioral scientist must
reference for studies of projects they will be asked to plan the method by which the community makes its
finance. The information gap can be closed by the choice among the final alternatives and associated
widespread dissemination of information such as that costs. Both economist and behavioral scientist should
collected during this study. There are two areas, how- be involved in the monitoring and evaluating phase of
ever, where concerted efforts will have to be made to project development.
permit a more equitable consideration of nonconven- The second area in which new incentives will be
tional solutions for sanitation. required for the promotion and adoption of appropriate
The first is a revision of the methods that have been sanitation technologies is that of financing. In many
used by consulting engineers and planners in selecting developed countries the central government provides
among technologies. The socioeconomic base for feasi- large subsidies or grants for the construction of inter-
bility planning must be improved. This probably means ceptors and sewage treatment plants.3 This obviously
that multidisciplinary teams-including an econo- makes it very difficult for a community to choose any
mist/planner and behavioral scientist as well as an other waste disposal system, since it would have to bear
engineer and financial analyst-should be used in the the alternative system's full financial cost.
first phase of planning and demand analysis. The An additional financial disincentive in some cases
amount of direct interaction with, and information has been the use of consultant fee schedules that have
gathering within, the community to be served should be been tied to a percentage of the construction costs of the
increased to provide better data for estimating future project the consultants design. Because it often takes
demands for different kinds of sanitation service. The more time and ingenuity to make a low-cost sanitation
demand analysis should be disaggregated according to technology such as vacuum cartage function at optimal
income, social status, housing, or other groupings that efficiency than it does to use tried and tested rules for
are likely to affect demand. In some cases, it will be sewerage design, it would be unfair to expect consul-
appropriate to look for the critical constraints to tants to design effective alternative systems for less
demand growth. For example, the growth of the water money. Yet this would be the result if their fees
supply system, and the rapidity with which new continue to be based on project costs.
connections can be made, may be a constraint to the International and bilateral lending agencies have
growth of a sewerage system that to function properly also exerted a financial bias toward sewerage systems
requires house connections for water. Similarly, if the in the past. Many made loans only to cover the foreign
local housing market is tight and the city is densifying exchange cost of projects. This meant that those tech-
rather than spreading as population increases, the nologies that were relatively intensive in imported
demand for new facilities (rather than the intensified equipment (and consultants) generated interest and
use of original facilities) is likely to be constrained. support from the agencies, whereas those that used
Income generally imposes another constraint on the mostly local materials, and perhaps even self-help
demand for sanitation services. Especially in areas construction, had too small a foreign exchange cost for
where the behavioral scientist finds that improved the agencies to be interested. Fortunately, most aid
sanitation is not a high priority of the inhabitants, the organizations, including the World Bank, have now
willingness of potential users to pay for any new system changed their policies to permit financing of projects'
is probably low.2 In poor areas, unless the residents have local cost components. There has also been increased
secure tenure on their property, they may be unwilling interest in financing projects whose benefits are di-
to pay anything for sanitation improvements they rected to the poorer groups in society. These two
cannot take along with them if they are forced to move. changes should promote the continuing, increased in-
If the estimation of demand does not take into account terest of aid organizations in low-cost sanitation pack-
factors such as these, it cannot provide a sound basis for ages.
the selection of technology. Along with such changes in the financial policies of
The contribution of the economist and behavioral aid organizations will have to come changes in the kinds
scientist to the feasibility study should not stop with the of institutional structures these agencies work through.
demand analysis. The economist's involvement in the Where household systems such as improved pit latrines
88 PROGRAM PLANNING AND DEVELOPMENT
are the appropriate technology, much of the construc- disposal. If the objective is improved community
tion work can probably be undertaken by the individual health, then they should make funds available for
households with supervision and technical assistance packages designed to achieve this goal at the least cost.
from a local organization. The best local organization These might include immunizational and educational
to provide this assistance may well be the health clinic components along with low-cost methods of waste
or agricultural cooperative, which may already have disposal. Even the most sophisticated sanitation tech-
local personnel and knowledge of the community, nology will not bring health improvements unless prop-
rather than the centralized water or sewerage author- erly used and combined with good users' habits of
ity. Channeling funds through an organization whose personal hygiene. If a government's objective is the
primary function is different from the activity being long-term protection of the environment, then it should
funded will certainly present unusual challenges in subsidize those technologies that promote this goal
promoting traditional cost recovery and management through dispersed recycling of treated waste. In gen-
objectives while retaining the independence of the eral, sewerage systems are not the least-cost way of
organization to pursue its primary responsibilities. achieving either better health or environmental protec-
As is emphasized elsewhere in this study, the prepa- tion. To subsidize them exclusively may preempt the
ration of low-cost sanitation projects is likely to require appropriate solution.
more time and local involvement than has been devoted Overall, the climate for a major breakthrough in
in the past to sewerage projects. Weak or nonexistent providing sanitation services to the large majority of
local institutions will present a more serious constraint people in developing countries who currently lack them
to project preparation, since much of the selection is probably better now than it has been in the past thirty
process depends on local understanding of the benefi- years. A continued effort to improve incentives and
ciaries' needs and preferences. It is difficult to substi- remove constraints to the choice of appropriate sanita-
tute foreign consultants for this, although it may be tion technologies can provide the needed groundwork
possible to use local university or municipal personnel. for such extended, global efforts as the International
In sum, the obstacles that have created a bias in favor Drinking Water Supply and Sanitation Decade of the
of sewerage in the past are gradually being overcome. 1980s.
Much of the necessary technical research into appro-
priate technologies for sanitation has been accom-
plished, and a widespread effort of dissemination must
now be made to close the information gap. Terms of Notes to Chapter 6
reference for sewerage projects are beginning to in-
clude the development of alternative sanitation compo- I. See Witold Rybczynski, Chongrak Polprasert, and Michael
nents. The importance of economic and social analysis McGarry, Low-Cost Technology OptionsforSanitation: A State-of-
to supplement technical and financial evaluations is the-Art Review and Annotated Bibliography [a joint effort by the
nowwideldand is beginning to find its way International Development Research Centre and the World Bank:
now widely accepted IDRC-102e/Appropriate Technologyfor WaterSupplyandSanita-
into feasibility studies. In addition, changes in the zion, vol. 4] (Ottawa: IDRC, 1978).
policies and objectives of international and bilateral 2. Willingness to pay, of course, is a broader concept than ability
lending agencies have created incentives to promote the to pay, and this applies to high-income areas as well as low-income
selection of more appropriate technologies. ones. If households already have well-functioning (and probably
The success record of individual government policies expensive) septic tanks to dispose of household wastes, householders
are unlikely to be willing to discontinue use of septic tanks for
thatd, coul encourage betr sanitation. progrramens is connection to a sewerage system even if they can afford to do so.
3. In the United States, for example, the government finances 75
developing countries need to consider carefully what percent of total construction costs, and states (such as California)
they hope to achieve through subsidizing costs for waste provide another 12 percent.
EA
7
Institutional Requirements
FOR THEIR SUCCESSFUL DEVELOPMENT and imple- the ability of the middle-class, urban consumer to
mentation, water supply and sanitation projects require preempt both government attention and funds. Factors
an institutional framework that allocates authority and contributing to disorganization are the lack of a com-
responsibility for each phase of a project. Policies, prehensive policy for the sector, a lack of understanding
organizational management, and financial resources of the benefits the sector provides (because they cannot
must be legally established to ensure continuity of be easily quantified), and a lack of knowledge about the
efforts in the sector. The institutional and policy re- low-cost technologies appropriate for service levels
quirements for a successful water supply and waste affordable by the urban and rural poor.
disposal program will be examined in the following Government support on a steady, long-term basis is
section; in brief, they are as follows: essential to avoid the destructive stop-and-go of pro-
gram preparation and implementation. Neither agen-
* A sector strategy supported by government cies nor communities nor users will make commitments
* Frequent reassessment of technologies and undertake construction if clear evidence of consis-
A stable, autonomous institution with clear respon- tent government support is not forthcoming. The sud-
sibilities dvlpnprgmancer _ den withdrawal of support-or failure to follow
Manpower development programs and career op- through once a project has been prepared-may
portunities in the sector (not only for technical, permanently discourage a community from undertak-
financial, and managerial staff but also for behav-
ioral scientists and health and community workers) inga scheduled project or supporting future ones.
* A tariff policy that ensures financial viability and .The reassessment of technology at frequentimtervals
encourages efficiency and equity. is necessary because of a natural tendency of designers
to base their selection on past, successful experiences
without necessarily considering present local conditions
in sufficient detail. This tendency is particularly rele-
Essential Components vant to the transfer of technologies from industrialized
to developing countries, where the requisite trained
Domestic water supply and excreta disposal are part manpower and access to equipment, spare parts, or
of the larger water supply and waste disposal sector, repair facilities frequently are not available. Further-
which itself may be part of a much larger sector such as more, the particular sociocultural environment can
water resources. In any case, specific sectoral policies preclude the acceptance of some technologies if major
and organizational arrangements should cover domes- educational efforts are not directed toward the in-
tic water supply and excreta disposal. In addition, tended beneficiary, and indigenous religious beliefs can
actions and policies of the health and education sectors prevent the use of others. Periodic monitoring of past
can have significant effects on water supply and sanita- projects, when coupled with analysis of specific, current
tion. The health ministry, for example, is frequently conditions, can enable an institution to learn from its
responsible for rural water supply and sanitation. own experience.
Sanitation projects often fail to achieve the objec- Stable, autonomous institutions offer career oppor-
tives they are designed to meet because the sector itself tunities that attract competent staff and can establish
is neglected, disorganized, or does not receive the financial and tariff policies that can enable the
necessary support from government. Neglect is usually institution to undertake long-term development pro-
greatest in rural areas, villages, small towns, urban grams without interruptions and excessive political
fringe areas, and slums. One reason for such neglect is interference. The two most important ingredients for
the high visibility of projects for major urban areas and the success of a water and sanitation agency are
89
90 PROGRAM PLANNING AND DEVELOPMENT
competent employees and sufficient funds. A staff * Government commitment to the program evi-
subject to dismissal with each political change loses denced by clear objectives, policies, and reliable
motivation and effectiveness. Funds that can be easily allocation of adequate staff and funds
diverted to other sectors to satisfy needs of other * Community participation in evaluation and selec-
constituencies delay implementation of sanitation tion of standards for service levels and appropriate
projects and, when they are required as matching technology
funds for borrowings, may postpone projects indefi- * Community participation in the construction and
nitely. Institutions should, therefore, be granted at selection of operating and maintenance arrange-
least the degree of autonomy that enables them to ments in communities too small for an independent
attract and keep effective staff and to set financial water and wastes agency
policies allowing the viability of their undertakings. * An efficient, well-staffed, and well-managed
In addition to simply attracting competent staff, an agency for technical support that, for communities
organization should offer salary increases and related too small for independent agencies, will: (1) plan
benefits to minimize staff turnover, including the provi- programs, provide guidelines and design assistance
sion of training programs to increase staff capacities. to local agencies and communities, monitor ongo-
Because public institutions are often unable to offer ing programs, evaluate completed projects, and
staff compensation equal to that prevailing in the ensure that lessons learned are reflected in new
private sector, trained staff often leave public service designs; (2) maintain close liaison among design,
after relatively short periods of employment. Such operating, and maintenance activities; (3) estab-
training still provides an overall economic benefit to the lish clear criteria for selection of materials and
country, but it follows for the public institution that equipment; (4) actively promote programs and
training programs must be continuous to ensure the assist communities in their implementation; and
availability of qualified candidates and to minimize (5) be sufficiently decentralized to assist commu-
institutional disruption. In addition, such career oppor- nities effectively.
tunities should be clearly identified through a program
for staff development and promotion.
Tariffs for services rendered not only provide for the Organizational Issues
financial viability of the executing agency but enable it
to cross-subsidize a minimal standard of service at One of the fundamental decisions to be made in
prices affordable to the poor and to encourage effi- organizing the water supply and sanitation sector is
ciency by charging the real cost of facilities to those whether the sector should be independent or combined
who can afford it. Appropriate tariff policies will with other municipal or social sectors. Successes and
reduce the need for government subsidies and thereby failures have been reported for both organizational
make the sector less dependent on scarce government approaches, and there are advantages and disadvan-
funds.' tages to both solutions. In urban areas there is usually
A sound tariff policy developed and supported at the an established organization that is responsible for
national level is usually necessary to ensure that needed municipal water supply and waste disposal. In large
increases in tariffs will not be delayed by local political cities, this is often an autonomous agency, whereas in
pressures. In addition, departments responsible for smaller cities it is frequently a department of the
planning or financing can develop guidelines to aid municipality or a part of a multisectoral agency. In
communities in determining the economic cost of the either case, the organization has staff competent in
services received for purposes of tariff setting and in conventional water supply and waste disposal technol-
designing tariff structures to provide cross-subsidies for ogy, although the degree of expertise and the availabil-
poorer consumers. As is true of technology selection, ity of financial resources to develop and implement
the basic tariff policy should be set at the national level, projects differ from municipality to municipality. Quite
and the application of the policy in a particular commu- often, municipal agencies or departments are assisted
nity should be left to the community organization. by a regional organization or a government agency that
is responsible for overall planning and that allocates
Policy Implementation funds to support sectoral institutions. Occasionally,
however, a regional or state agency is responsible not
For water supply and excreta disposal projects incor- only for the planning but also for the implementation
porating other than conventional technologies, further and subsequent operation and maintenance of water
institutional and policy strategies should provide for: and sewer systems in the area of its jurisdiction.
INSTITUTIONAL REQUIREMENTS 91
In contrast to urban water supply and sewage dis- Division of Responsibilities
posal, small towns and rural areas are less able to take
care of their own needs because their inhabitants are Whether urban or rural, single- or multisectoral, the
generally not as well off and, therefore, are financially institutions and agencies involved in water supply and
less able to support the institutions capable of providing excreta disposal must have a clear division of responsi-
adequate services. One solution to this problem that has bilities. It is not as important to decide which functions
often achieved notable results is the combination of are assigned to each as it is to avoid overlaps and gaps in
various productive and social components in rural responsibilities. A generalized example of the various
development projects. In such integrated development agencies and accompanying functions likely to be
projects, the water supply and sanitation component involved in water and sanitation program planning and
benefits from the organization, management, and (pos- execution is shown in table 7-1.
sibly) the income of the project's productive compo- Obviously, this tabulation represents a single, rela-
nents. Nevertheless, these projects often suffer from the tively simple scheme that will have to be adapted
same problem encountered with rural water supply and to each specific case. It lists technical organizations
sanitation systems in general: inadequate operation and with a direct involvement in the sector and does not
maintenance that leads to a rapid deterioration of the include such related activities as general education,
facilities. As a general rule, a single, sectoral agency health education, training in personal hygiene, nutri-
that has been organized to provide support to small tion, health services, and so forth. All these activities
community organizations is preferable to a multi- are important, however, and the full benefits of water
sectoral institution because the organizational, supply and sanitation often cannot be realized without
managerial, and personnel needs of the former are considering them.
likely to be known and more easily met than those of the Staff development and training programs, for exam-
latter. ple, must be based on the instruction of selected
Another critical decision to be made in organizing individuals and should make use of existing educational
the water and sanitation sector is the extent of central- infrastructure. Thus, the ministry of education plays an
ization or decentralization of control. Whatever the important role in the training of staff for the water
organizational arrangement, there should be a national supply and sanitation sector. The same ministry may
policy and planning body; national (in small countries), also be responsible for health education, nutrition, and
state, or municipal operating agencies for project plan- so forth. Alternatively, these supportive activities may
ning, implementation, operation, and maintenance; be the responsibility of the agricultural extension ser-
and local community units with responsibility for fi- vice or ministry of health. Nevertheless, inclusion of
nal technology selection, operation, and maintenance. these related functions in the simplified schematic of
There obviously are many solutions, with the allocation table 7-1 would have complicated the presentation
of responsibility dependent on local conditions. Often unnecessarily. The important point for planners to
the reasons for the choice of an organization are remember is the need to consider these intersectoral,
historical. For example, state organizations based on organizational issues in both the assignment of institu-
political boundaries are more common than agencies tional responsibilities and the design and implementa-
based on topographical boundaries (for example, river tion of projects. The maximal use of the agency with
basin authorities), even though the latter are usually primary responsibility and expertise in the given area is
better suited to dealing with sectoral problems. Both usually the best solution.
the costs and benefits of any suitable organizational set- In practice, the organizational arrangements will
up should be evaluated before the structure is adopted. probably never be as simple, and responsibilities so
A good organizational structure provides for maxi- clearly defined, as indicated in the table. For example,
mum participation by communities, particularly in the in many countries the responsibility for urban and rural
rural areas where social and cultural considerations are areas is allocated to different ministries. Even within
important in selecting standards of service and, thus, urban and rural areas, there may be different responsi-
the sanitation system's construction and operating ble ministries or various agencies within ministries.
costs. There appear to be fewer cultural constraints in Furthermore, communities are dynamic. They
urban areas, probably because immigrants to the city naturally grow and develop and, thus, can move from
have already accepted the need to adapt to a different one jurisdiction to another.
life style. There is no standard form such community Ideally, the sector should be properly organized
participation should take, but chapter 5 of this report before projects are designed and implemented. It is
provides some guidelines for its design. rarely possible, however, to achieve this objective in
92 PROGRAM PLANNING AND DEVELOPMENT
Table 7-1. Institutional Responsibilities in Sanitation
Level of institutional responsibility Function
National legislature Review and approval of policies; establish-
ment of enabling legislation
Ministry of economic planning, hydraulic resources, Long-term planning; allocation of national
public works, and the like and foreign financial resources
Public utility commission (or planning unit) Planning of policies and sectoral priorities;
review of tariffs; development of sectoral
manpower
Sectoral finance agency Financing and financial policies
Ministry of health Establishment and monitoring of quality
standards
State or province
Public utility department or planning unit Detailed planning; allocation of state re-
sources
Water supply and sanitation agencv Implementation of national policies; design
or multisectoral development agency and construction; monitoring. supervision,
and support of local authorities; manpower
training; operational and maintenance
backup for small systems
Local
Municipal department or municipal authority Design;;} construction; operation and main-
tenance, on-the-job training
Water and sanitation committee of small Construction; operation and maintenance
community or cooperative
a. Unless performed by the state agency.
practice within a short period of time. The overall project with technical support; and a community orga-
organizational objectives of the sector should therefore nization, committee, or leader to provide the link
be considered as long-range goals, with the institutional between users and agency. Although not interchange-
arrangements that will eventually lead to their attain- able, these required levels of institutional organization
ment (or that, at least, will not prevent their clarifica- are interdependent and reciprocal. Projects and pro-
tion and development) being designed for specific grams can be initiated at any of the three levels as long
projects and programs. as they fulfill the requirements of the other two.
In sum, it is the finding of this study that the
irreducible, minimal institutional requirements for the
successful implementation of community water supply Note to Chapter 7
and sanitation projects are: a government (national or
and saitatio projets are a govrnment(natioal or . For a discussion of water tariff design based on principles of
state) policy that supports the project; a sectoral agency marginal cost pricing, see J. J. Warford and D. S. Julius, "Water
at the regional (for rural areas) or community (for Rates in Developing Countries," Journal of the American Water
large cities or metropolitan areas) level to provide the Works Association (April 1979), pp. 199-203.
8
Community Participation and Organization
CONVENTIONAL WATER SUPPLY and sewerage projects Objectives
are usually designed without community participation;
that is, the beneficiaries are not directly consulted or The objectives of community participation in sanita-
involved in the design, implementation, or operation of tion are the selection of:
the facilities. In fact, public involvement is often consid-
ered of little value at best and a hindrance to progress at * Technologies that are acceptable to the community
worst. That sanitary engineers get away with this atti- and that offer benefits the community considers
tude and proponents of nuclear energy, for example, do important at a cost it can afford
not is probably because sewerage is an established tech- * The most effective materials and methods of
nology and nuclear power plants are new and controver- constructing the appropriate facilities
sial. Few members of a community to be served by a * Technologies that can be operated and maintained
new sanitation system ask the question whether the by the local population with minimal assistance
conventional sanitation technology is the best or the from outside agencies.
only feasible method of providing the intended service. To achieve a successful project, the community's
In the urban areas of developing countries, the lack participation should extend from the initial collection
of community participation has resulted in water and of data and identification of users' preferences
sewerage systems' being constructed according to the through the design and construction stage to the
models of those built in industrialized countries. This permanent operation and maintenance of the facilities.
simple adoption of advanced technology has provided The form of participation and the extent of commu-
reasonable water service to the middle- and upper- nity involvement will vary. A community on the urban
income populations and sewerage to those in very dense fringe (for example, a slum being upgraded) can
and high-income areas. The high cost of conventional probably count on the city sanitation organization's
sewerage, however, has inevitably meant that scanty or providing municipal water and sewerage services to
no facilities could be provided for the poor. The implement and operate communal facilities. Here,
situation is even worse outside major cities. In rural community participation will be concerned primarily
areas, the lack of funds is made worse by the absence of with the selection of levels of service that reflect the
sectoral institutions capable of operating and maintain- community's needs and willingness to pay. Rural
ing conventional facilities. communities, however, need to develop a system they
Increasing the present low levels of sanitation service can operate and maintain with a minimum of external
will require either a massive infusion of funds and the assistance. This usually means local, part-time man-
creation of large service organizations or the use of agement and operation supplemented by advice and
technologies that are less expensive than sewerage and assistance from a regional organization for technical
easier for users and smaller communities to operate and support.
maintain. With funds limited, the use of alternative
sanitation technologies clearly offers a greater possibil-
ity for realization of this goal, but it will also require Scope
greater involvement by beneficiaries in smaller towns
and rural areas to compensate for the absence of a To achieve the objectives of community participation
strong, centralized institution. in sanitation, the organizational program must include:'
93
94 PROGRAM PLANNING AND DEVELOPMENT
� Identification of formal or informal channels for * Organization of the construction and execution of
community leadership and communication the work
* Determination of the community's existing prac- * Continued activities of operation, maintenance, and
tices for water use and excreta disposal and its monitoring, including the assessment and collection
attitudes toward them of fees.
* Determination of the community's willingness to
pay for desired improvements through cash con- The first three tasks should be undertaken at the very
tributions, labor, or materials beginning of project development (they are, incidentally,
* Organization and execution of any self-help con- part of stage I in figure I -1), the fourth toward the end
struction agreed upon of the selection phase (stage 6 of figure 1-1), and the
* Operation and maintenance of communal facilities, final two must be scheduled to meet technical require-
assistance to users in maintaining individual ments and community work pattemns.
facilities, and collection of funds. The first task uses unstructured interviews to deter-
There are mnmtdadmine local attitudes and perceptions that can affect the
There ar many methodspandmndelstforynitiatingbte choice of sanitation technology and enginecring design.
process of community participatlon that may be suitable Among the factors to be considered here are preferences
for different communities. Obviously, the approach must for private or communal facilities- importance of the
fit the particular community, and what is suitable in one fac.iitie lorcaton,ucapaci aility, adporivanc the
culture may not be appropriate in another. Regardless of f
the agency or organization responsible for initiating importance of aesthetic features such as the design of the
sanitation projects, a team including behavioral scien- superstructure or color of the interior; local traditions
tists, community extensionwore, ad e s is concerning conservation, reuse, or reclamation of water
tisbabs, comm sunityblextenion workemers,ia eng rs is and waste; the importance of local autonomy versus
probably most suitable for implementng a program for confidence in regional or national authorities; and the
community artician at th least, st tea sod existence of cooperative arrangements, either formal or
consist of a technician familiar with low-cost water and ifra.Ohrfcosaotwihifraini
sanitation technology and a person (preferably female)
with expertise in public health education, personal essential for design or implementation include: land
hygiene, and nutrition. Both should be employees of the tenure; the customary manner in which local committees
agency responsible for providing the comunitare formed and contributions in time, money, or
agency responsible for providing the community with maeilarmdetco unypojtsadth
technical support and should have access to agency maerians byewhic community ma ojety or cosens
specialists such as hydrogeologists, well drillers, engi- bae obtained.
neers, economists, behavioral scientists, health special-
ists, and the like. The involvement of the community The second task consists of the preparation and testing
leadership is important for the success of chpommuni of a questionnaire for structured interviews. Specific
regardless of the method used to implement the questions are needed to get specific answers. The type of
program. questionnaire used in the World Bank case studies was
described in chapter 5, and it can serve as a basis for
developing locally relevant questions.
Implementation The third task is the formal interviewing of a
representative sample of the community. It is not
The following tasks can be identified as the minimum necessary to conduct a census of the entire community if
for a community participation program that will lead to the sample is selected with the cooperation of the
community's leaders. Household interviews should in-
asuccessful project. Each will be dicussed in turinthis clude women, since they are both knowledgeable about
water use and responsible for training children in
* Unstructured interviews with community leadership personal hygiene and sanitation. The interviewer should
and a limited number of users to identify users' always remember that the most reliable answers to
attitudes and preferences questions on sanitation will come from those who are
* Design and testing of a questionnaire for structured most concerned about sanitation, and these responses
interviews will be given most candidly to an interviewer who is
* Structured interviews conducted with a representa- perceived to understand and empathize with the
tive sample of households respondents. Selection of interviewers from the same
* Presentation of feasible technologies and their costs population group and with a similar socioeconomic
to the community or its leaders to deternine background is therefore extremely important. After the
willingness to pay formal interviews, the responses should be evaluated
COMMUNITY PARTICIPATION AND ORGANIZATION 95
jointly by the behavioral scientist and engineer of the facilities; the delivery of materials provided in lieu of
project team. Information collected during the unstruc- cash contributions; the organizing of work parties and
tured interviews should be used to put the questionnaires' the keeping of records of time, cash, or materials
results into perspective. If, for example, land tenure or provided by community members; the supplying of
employment was found to be a strong priority during the technical assistance for the construction and initial
unstructured parts of an interview, sanitation problems operation of the facilities; and the coordination of
will get little attention from the householder. external assistance from the technical support agency.
The information on community preferences and If there is a formal organizational structure in the
attitudes should be used by the engineer to design community, it may be used to facilitate project
acceptable sanitation alternatives. Once these have been implementation and operation. If no structure exists,
costed, a meeting should be held between the project special organizational arrangements will have to be
team and the community or its representatives at which made for the project. Such arrangements can range from
the alternative technologies and their costs should be the selection of a local craftsman who will periodically
discussed (the fourth task). Photographs and working check a piece of equipment to the hiring of full-time staff
models should be presented and explained, particularly for operating and maintaining a communal facility. Just
in areas where written communication is not widely as in the selection of the technology, the type of
used. The benefits of each level of service and the organizational arrangement should be a community
manner in which each alternative can be upgraded decision.
should be discussed. If necessary, limited demonstration The sixth task encompasses the regular operation,
projects may be built. In any event, the community's maintenance, and monitoring of the facilities. The
choice of technologies and willingness to pay should be monitoring program should include the dissemination of
determined at or following this meeting. the information collected for the project to other
If an interested majority within the community does communities, so that lessons learned from the success or
not develop in about a month after the meeting, it will failure in one location can be used in the design and
ordinarily be better to shift the project and resources to implementation of programs in others. The monitoring
another community. Important differences between should also include the exchange of visits by those
community preference and design or between levels of responsible for the operation and maintenance of similar
service (whether higher or lower) are seldom resolved by facilities in various other communities and, if systems are
more education or information, and voluntary schemes large or sophisticated enough, the training of local
in which wealthier individuals are asked to support personnel at regional agency headquarters. Any training
sanitation services for others usually do not work. For not accomplished under the fourth and fifth tasks above
example, wealthy homeowners are not likely to abandon should take place now, and the relation between the
functioning septic tanks and pay high charges for sewer operators and the technician should be established. The
connection so that poor neighborhoods can be served by technician should make periodic visits to the community
the same sewer system. Either in parallel with the to help solve minor problems, provide routine technical
selection of technology or as a result of it, the community assistance, order spare parts, and mobilize additional
will have to organize the implementation and subsequent support if major problems arise. These visits should be
operation and maintenance of the facilities to be regular and made at short intervals in the beginning of
constructed (the fifth and sixth tasks). operations and at least once a month after the
The fifth task follows on the selection of technology community has become familiar with the tasks of
and is the time when the choice of implementing operating the facilities. Provision also should be made for
procedure (for example, self-help labor, contracting, or a rapid contact in cases of emergency (such as the failure
mix of the two) and organization is made and the of equipment, suspected water contamination, and the
construction is undertaken. Construction work should be like).
performed with the assistance of the technician from the
technical support agency (but under local leadership, if
possible). For continuity, it is important that the Linkage of the Institution and Community
technician train at least one person in the community for
this task as the participatory process proceeds. As the preceding description of tasks suggests, many
Some of the activities involved in a successful aspects of the community's participation in sanitation
construction program are the selection of the sites for program development depend upon and influence insti-
communal and private facilities; the purchase of tutional structures. Although the previous chapter dealt
materials not available in the community; the sale or specifically with institutional issues, it may be useful to
distribution of materials needed to construct individual conclude this chapter with a simplified description of the
96 PROGRAM PLANNING AND DEVELOPMENT
institutional steps required to facilitate and support and monitors for completed projects; assign all other
community involvement. These policies should include extension workers to new areas to replicate success-
measures to: ful projects
* Provide technical assistance and support; maintain
*Establish a support unit for water supply and the stock of spare parts
sanitation in existing regional agencies or form an * Monitor the operation and quality of service;
independent support unit (the specialists likely to be disto e iopration; and prolide c ontinuou
involved include engineers, hydrogeologists, a be- tinseing p r forncomn and local
havioral scientist, an economist, an accountant, a staff.
plumber, a mechanic, an electrician, a well driller, a
purchasing agent, and a health educator) In sum, community participation and the assessment
�Organize and staff a central support unit; establish of a community's willingness to pay for improved service
design and operating standards and select the levels through contributions of money, labor, or ma-
villages or the criteria by which priority is assigned; terials depend fundamentally upon household income
conduct specialized tasks such as hydrogeological levels and perceived needs. This assessment is affected
surveys, management training, or operating assis- by the accuracy, completeness, and timeliness of the
tance information that is exchanged between the residents and
* Train community workers in low-cost technologies those who are conducting the feasibility study. Analysis
for water supply and sanitation and in community of social factors and the conduct of interviews should be
organization the responsibility of community members or people
* Train community workers in health care and accepted by the community; these tasks are too
nutrition important to be entrusted to strangers.
* Canvass and organize selected communities; plan,
design, and implement prototype projects to com-
plete the training of community workers Note to Chapter 8
* Assign community workers or teams to designated
areas to canvass and organize communities 1. This list has been developed in part from work by A. U. White
�Assist co.nmunities in constructing facilitis .and G. F. White, "Behavioral Factors in Selection of Technologies,"
* ASSISt conuriunities in constructing facilities in Appropriate Technology in Water Supply and Waste Disposal,
* Maintain a limited number of community workers ed. Charles G. Gunnerson and John M. Kalbermatten (New York:
as itinerant maintenance and operations advisers American Society of Civil Engineers, 1979). pp. 31-52.
9
Project Development
WITHIN THE FRAMEWORK for institutional and com- known and universally accepted that any discussion of
munity involvement in the planning of sanitation alternative technology is not considered necessary.
programs discussed in previous chapters, the develop- Rarely, if ever, is a community consulted on the level
ment of individual sanitation projects will be accom- of service to be provided, and decisions are usually
plished by different approaches in different settings. made by the agency or the municipal government.
This chapter considers three of the most probable The major drawback of conventional projects has
settings for project development and presents a been their cost, which effectively has prevented the
method for the selection and upgrading of technology. extension of water supply and sewerage services to all
inhabitants of a community. Usually the downtown
areas and middle-class districts of cities are the first
Types of Sanitation Projects recipients of water supply and sewerage services.
Water supply at a lower level of service (for example,
The urban or rural setting for a sanitation project, public standpipes) is often extended to other areas of a
as well as the particularities of the site, will influence city, but sewerage is rarely, if ever, constructed in
the choice of appropriate technology (see chapters 1 districts other than the high-density areas during the
and 2). Similarly, the institutional structure through first stages of a master plan's implementation. This
which an urban sanitation project is developed and state of affairs is a reflection both of the high cost of
implemented will be different for a project designed sewerage (and its requirement for water connections)
specifically for water supply and sanitation and for one and the prevalent attitude that the only acceptable
designed for general urban development. These differ- method of excreta disposal is waterborne sewerage.
ences will be examined in the following subsections. People unable to pay the high cost of sewerage simply
have to forgo the service.
To serve the entire population of a community at a
Urban waterupansewragprice it can afford, a change is required in the
Conventional sanitation projects are usually devel- development of master plans for sanitation. Terms of
oped through well-defined stages, beginning with a reference should specifically require that consultants
master plan for an urban community or region. Such a evaluate not only the potential development of
plan generally defines stages of implementation and is sewerage for some areas but also the provision of
followed by feasibility studies for individual stages or sanitation services for the entire community. This
projects, which are followed in turn by detailed design change in planning will identify areas for which
and construction. All these studies and designs can be sewerage is the correct solution and areas for which
done by the sanitation institution, although the work is other methods of sanitation are appropriate. These
more often contracted to consulting engineers. Con- latter alternative sanitation services should be de-
struction of small projects is often performed by the signed to be gradually upgraded as water consumption
sectoral agency, whereas major projects are generally increases and the incomes of the users grow. There-
constructed by contract, with only the supervision of fore, a master plan should provide for the implementa-
construction provided by agency staff. tion of waste disposal systems for an entire urban area,
Community participation in conventional water identifying not only the various stages of a sewerage
supply and sewerage projects is minimal. Projects are scheme for affluent and downtown areas but also the
generally designed to satisfy existing or forecasted appropriate sanitation technologies and their upgrad-
demands, and the solution employed is usually so well ing sequences for other areas of the city. Similarly, the
97
98 PROGRAM PLANNING AND DEVELOPMENT
water supply component should provide for a mix of done so that future integration of the facilities into a
service standards that can be gradually improved as municipal network can be accomplished at least cost.
the demand from, and the financial resources of, Whether a water supply and sewerage agency should
consumers increases.' provide planning and implementation services to the
A major departure from the traditional approach to multisectoral project, or whether the project should do
the development of urban water supply and sewerage its own planning and implementation with the help of
systems is the requirement that the master plan consultants, must be decided for each individual case.
consider several technologies and that the subsequent In any event, it is best that the municipal water and
feasibility, design, construction, and operating stages sewerage agency be responsible for operation and
reflect the progress over time of each of the alternative maintenance after the system is put into service.
technologies to be used. Another, additional revision of One of the distinguishing features of urban devel-
previous practice is that, in the selection of alternative opment projects-and particularly of "sites-and-ser-
sanitation technologies, the community to be served be vices"' and slum-upgrading projects-is the active
included in the choice of a technology that will match participation of the community. This participatory
its preferences and needs. Organizing the community process can easily be extended to include water supply
for operation and maintenance of the chosen technol- and sanitation. As in previously described projects,
ogy will ordinarily not be required because the existing community participation would be primarily in the
municipal organization should be capable of providing selection of technology rather than in the organization
the necessary services. of operation and maintenapce. An exception is the
Preparation of such a master plan obviously case in which a new community must provide its own
requires additional and different skills, and consul- infrastructural services. In this case, of course, the
tants should be selected and compensated accordingly. process of community participation will have to
Consultants need to have on their staff specialists in include the establishment of the necessary organiza-
the behavioral sciences, community organization, tion for operating and maintaining communal sanita-
economics, sanitation, public health, low-cost con- tion facilities.
struction, and personnel training. This last specialist
will have to devise and implement training programs
for local staff, so that they acquire the skills necessary Rural water supply and sanitation
to undertake similar projects elsewhere in the region. The provision of water supply and sanitation to
Most consultants will initially have to train their own rural areas has traditionally been the most intractable
staffs in the design of nonconventional sanitation problem in the sector, basically because rural commu-
projects. nities are too small to support their own viable
infrastructural agencies. Rural areas also have often
Urban development been neglected in national or regional planning for
water supply and sanitation. An additional reason for
Urban water supply and sewerage are provided not the neglect has been that the technologies for water
only by agencies directly responsible for these sectors supply and sanitation have been developed primarily
but also by a variety of organizations responsible for for the benefit of urban populations. In sanitation
the design and implementation of multisectoral proj- technology particularly, a gap exists today between
ects-such as urban development, slum upgrading, what is affordable in a rural community and what is
development of satellite communities, and the like. provided as standard practice in the urban commu-
Responsibility for the provision of water supply and nity. Because urban communities more often contain a
sewerage for such projects may rest with a municipal mix of income levels than do rural ones, the potential
water and sewerage agency, which will likely follow its for cross-subsidizing poorer residents is lower in rural
established procedures for project development and communities.
implementation. Alternatively, a development agency For lasting success, projects for rural water supply
may design and implement the project independently and sanitation require the government's commitment,
or work under various cooperative arrangements with an agency to provide technical support, and commu-
a water supply and sewerage institution. nity participation. It takes time, of course, to translate
Whatever the institutional arrangements, a multi- governmental support into effective policies and
disciplinary project would, ideally, implement already direction, and it also takes time to establish an
defined sectoral plans. But very often sectoral plans do effective organization for technical support at the
not exist (see chapter 7) or do not cover all the areas regional level. A judgment has to be made in each case
involved. Some ad hoc sectoral planning must then be on how far the process of translating the government's
PROJECT DEVELOPMENT 99
commitment into substantive action and of imple- An algorithm, which can be used as a step-by-step
menting an organization for technical support must guide to the selection of the most appropriate
proceed before communities can be helped in their sanitation technology for any given community in the
desire to improve their water supply and sanitation developing countries, is presented (in stages) through-
services. The type of sanitation technology to be used out figures 9-1 through 9-3. The algorithm is intended
has an important bearing on this judgment because, if only as a guide to the decisionmaking process. Its main
only minimal funding and technical support will be virtue is that it can stimulate engineers and planners to
required, then assistance to the community plays a less ask the right kinds of questions, the sort they may not
important role in the project's eventual success. In any ask otherwise. Some of the answers to these questions
case, great care has to be taken not to raise can only be obtained from the intended beneficiaries
expectations that may not be fulfilled. (see chapter 8). Although it is believed that the
Rural water supply and sanitation projects require a algorithm is directly applicable to most situations
comprehensive governmental policy on how rural encountered in developing countries, there will always
needs for infrastructure are to be met and financed. be the occasional combination of circumstances for
Criteria for the selection of communities and for which the most appropriate option is not the one the
standard project design should be established by the algorithm suggests. This analytical device should not,
technical support agency responsible for the area in therefore, be used blindly in the place of engineering
question. Based on these policies and criteria, the judgment but, rather, as a tool for facilitating the
technical support agency should train community critical appraisal of various sanitation options, espe-
workers in appropriate water supply and sanitation cially those for the urban and rural poor.
technology, health education (particularly personal The algorithm is most useful when there is no
hygiene), and nutrition. In addition, the community existing (formal) sanitation in the community under
workers should receive comprehensive training in how consideration. In general, any existing household
to generate community participation and how to sanitation systems, except perhaps unimproved pit and
organize a community in the implementation and bucket latrines, will influence the technology chosen to
subsequent operation and maintenance of the facili- improve excreta and sullage disposal in ways the
ties. algorithm cannot fully capture. In addition, it is
important to consider the sanitation facilities existing
or planned in neighboring areas because these facili-
Technology Selection ties may enable the community to reduce its costs
below what they would otherwise be, thereby provid-
In the foregoing section, three standard settings for ing additional affordable alternatives. Here and in the
sanitation projects were described. In the sections that algorithm, affordability is taken to embrace both
follow, information presented in preceding chapters economic and financial affordability at the household,
will be used to develop an analytical method for the municipal, and national levels-including the question
design of sanitation projects in a particular setting and of subsidies-as discussed in chapter 3.
sequences for modifying appropriate technology to The selection process starts, in figure 9-1, by asking
meet users' changing needs for improved service. if there is, or soon will be, water supply service to the
Once a community has been selected for sanitation houses under consideration. This is a critical question,
improvements, the planner of sanitation projects must since its answer immediately determines whether
select from those technologies appropriate to the needs conventional sewerage is a possible option or not. If the
and resources of the community. This selection should water supply service is through house connections, if
be based on a combination of economic, technical, and there are no social or environmental reasons for
social criteria, and these issues often reduce to the excluding sewerage, and if it can be afforded-then
single question: what is the least expensive, technically conventional sewerage is chosen (unless there is
feasible technology that the users will accept and can sufficient land and less cost for septic tanks with
maintain and that the local authority is institutionally soakaways). Septic tanks with drainage fields would
capable of operating? This question may not pertain in be the technology of preference where water-saving
communities (or areas of cities) with higher income appliances-such as cistern-flush toilets using less
levels, in which consumers may prefer and be willing than I gallon (3.8 liters) of water-can be installed to
to pay for higher service standards. The cheapest make them feasible.
technology may not always be the one that should be If a community does not have, and is not likely to
chosen, but it certainly must be determined if the full have, house water connections, then cistern-flush
range of alternatives is to be explored. toilets and conventional sewerage cannot be used. If
100 PROGRAM PLANNING AND DEVELOPMENT
Figure 9-1. First-stage Algorithm for Selection of Sanitation Technology
Start
Are there water tap, No Is the wastec.atcr No Go to seeiond-stagc
In the houses lo he ------ 11- flow greater thian alGorithm S'nd ma;wKe
scricdno 51) liters suItablc arrangements
scrvcd ~~~~~~~~per capita dailvy? for sullagc disptosal
Yes Yes
Arc thcre strong
social or etstiron- No Is there a strong Yes
mental reasons that social preference
precu dc the ase torueeeea
of consen tionaltoruexcta
scweragel
No No
Are sCwCrCd pouT- No
_ flush (PT ) torilets
Pr toilets
1sthc suit No
permeabcnl' o No --N Arc sewers Ycs
on-site dispzsal J t affordable" ? Sewerage
of swptic tank _ s
effuentn
lYes
Arg gene atet sizcs Can i atcr consumptitn
c a rgt dnilugh for No he reduced so that No N( o
e sp t i c tanks fnd oon-sit dispsal of Mla
soakt,ivesy s septac tank sffluent
Yes Yes No
1 r < 9 1 Ycs | ~~~~~~~~~~~Are sep ti :X n Y Sclepti lank,
aciiesszeh nc t lingaul affordmbpc sin Dd C)tkilts an th
seweralg U
sullage generated on site is sufficient (>50 liters per subsequent se wered PF system is not
capita daily) to enable a sewered pour-flush (PF) appropriate, the choice lies among the various on-site
system to function satisfactorily, a sewered PF system excreta disposal technologies with appropriate facili-
can be used provided that: it is cheaper than ties for the disposal of sullage (see the selection
alternative systems with separate sullage disposal process for these in figure 9-2).
facilities or the users, or the municipality are willing to If double-vault composting (DVC) toilets and three-
pay the extra cost, and there is no overriding social stage septic tank systems cannot be used, the choice
preference for night soil to be collected separately for lies between ventilated improved pit (VIP) latrines,
PROJECT DEVELOPMENT 101
Reed Odorless Earth Closets (ROECs), PF toilets, vault socioeconomic status). Such feasible sequences, or
toilets, and communal sanitation blocks as determined stages for upgrading, are summarized in figure 9-4.
by the algorithm in figure 9-3. The advantages and
disadvantages of these technologies and their applica- DVC toilets and three-stage septic tanks
bility under different conditions have been discussed in
chapter 2. These toilets, functioning well and with a continuing
Once the most appropriate technology has been demand for compost or fertilizer, need no upgrading.
selected by using the algorithm, several questions Upgrading of the water supply from hand-carried to
should be asked as checks. These are: household service, increased housing density, or
decreased demand for compost would, however,
. Can the existing sanitation system (if any) be require modifications in these facilities. The toilets
upgraded in any better way than that suggested could be easily modified to PF vault toilets or to vaults
by the algorithm? with vacuum-truck collection.
* Is the proposed technology socially acceptable? Is
it compatible with cultural and religious require-
ments? Can it be maintained by the user and, if VIP latrines and ROECs
appropriate, by the municipality? Are municipal Many rural and suburban water and sanitation
support services (for example, education and projects provide pit latrines and communal hand-
inspection) required? Can they be made avail- pumps or public standpipes as the initial improvement.
able? The pit latrine should be either a VIP latrine or ROEC.
. Is the technology politically acceptable? The subsequent priority for improvement would most
*Are the consumers willing to pay the full cost of likely be upgrading the water supply to yard taps (or
the proposed technology? If not, are user subsidies household handpumps where applicable). Both the ViP
(direct grants or "soft" loans) available? Is latrines and ROECs could then be upgraded to PF
foreign exchange required? toilets. The conversion of a ROEC to a PF toilet is very
. What is the expected upgrading sequence? What simple and inexpensive: a water-seal squatting plate or
period of time is involved? Is it compatible with pedestal seat is installed in place of the ROEC chute,
current housing and water development plans? and the existing displaced pit is used to receive the
Are more costly technologies in the upgrading flush water. Depending on soil conditions it may be
sequence affordable and desired now? necessary to enlarge the pit to provide more infiltra-
. What facilities exist to produce the hardware tion area for the flush water. Alternatively, a second
required for the technology? If lacking, can they pit or infiltration trench could be provided to receive
be developed? Are the necessary raw materials the settled flush water from the original pit.
locally available? Can self-help labor be used? A VIP latrine can also be converted to a PF toilet by
Are training programs required? filling in the pit with soil and installing a water-seal
* If the technology cannot dispose of sullage, can unit that is connected to a newly dug pit. Clearly, this
adequate facilities for sullage disposal be in- is best done when the pit is close to the end of its life,
stalled? Is the amount of sullage low enough (or and it is most advantageous when the superstructure
could it be reduced) to avoid the need for sullage cannot easily be dismantled (for example, the super-
disposal facilities? structure is constructed in concrete block or adobe
brick).
Sanitation Sequences
PF toilets
The selection of the technology best suited to effect When the water supply is upgraded to house
initial improvements in sanitation for a particular area connections, it is possible to install a low-volume,
has been discussed in the preceding section. This cistern-flush toilet. This is not essential and may not
selection should, however, also reflect the future need be considered a priority by the users, to whom
for improvements as the users' aspirations and upgrading of the water supply from a single yard tap
socioeconomic status rise. The following subsections to multiple house connections usually first means
examine the feasibility of upgrading sanitation in plumbing for kitchens and bathing areas. The main
stages that take into account incremental improve- improvement required is better sullage disposal that
ments in the level of water supply service (improve- does not have to be via sewers. One such conversion
ments that are themselves, of course, measures of requires:
Figure 9-2. Second-stage Algorithm for Selection of Sanitation Technology
Start
Is there art LtvvunetTd u5s Yes Is r-euse of liquidI prcefcrred Yes Is sutiffcicnt Water Ystre-ag Yes
for coipost or st a ilizcva Are septic Three-sta
bun-ms by houischold or oveeretae ofcmoseovilabt? frP:tanks affordable? septic tanks
others'? xrt'olt
No iNo No No
ts sufficient=organic waste Yes Can doubic-vault Yes eAre DV toilet Ys
K) ~ ~ ~ ~ ~ ~ ~~~~~~~~~~~~~ssfiintogii at0compostinig (u)vc) toilets Ar vOolt VO
material or ash available? be expected to be affordable? toilets
well mnaintaiined?
|No No |No
Arc ventilatedYe
improved double- esIDP
pit (vioP) latrincs latrines
affordable?
No
No F Go to third-stagc
algorithim
Figure 9-3. Third-stage Algorithm for Selection of Sanitation Technology
Start
iiiorc than I mctcr Is soil sufficientlv clcansing materials ~~~~~~~Affc Pr tiletsiet
s | ~~~~~Are Reed Oedorless |Yes ||Yes
be raised? _ peferred over vip affoirdable? RF'
No Areavu,riatrineseYe''H,
>_ | No ANo b t ~~~~~~~~~~~ ~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~attordabj^ |t littrilie,
jP No Commun.t
sanitatiofn
No facilities
Is there sulihcient
,palce tor aI perm.lnent Yes Are V'IDP Ycs bVD
doutlic-pit systern 0 latrines l atrne
with a minipilum of I affordable'?
air storage per tilultl'
No
Is thcrc either :a Yesc r al olt YeVal
nmunicipid or pri- . Ar al eies sVul
%atle s\stcni for affordabic' ? olodets
cruipt\ing laltrines?
No No Communal
sanitulion
facilities
104 PROGRAM PLANNING AND DEVELOPMENT
Figure 9-4. Potential Sanitation Sequences
Level of water service
Satlitation
techInolog,y
Hand- Yard ratp or House
carried household pump connection
Composting toilets
Double-vault
Vaults
Septic tank (Unlikelyl)
Vault and
vacuum truck (Unlikely)
Improved pit latrines
vip latrinc and
VIDP latrine (Unlikely)
ROECi (Unlikely)
PF toilct +>O+<:
Sewerage
Small-bore
se we red
PF toilet Q
Conventional
sewerage or
septic tank Q )
O lTechnically feasibic.
* Feasible if sufficient pour-flush uxzater will he hand carried
o Tcchnicallv infeasible.
O Feasible if total wastewsater how exceeds 511 liters per capita daily.
PROJECT DEVELOPMENT 105
* Construction of a small, single-chamber septic for ten years, after which either the next stage will be
tank close to the existing PF pit and discharge of added or the existing facility will be replaced or
the sullage directly into it (the tank should provide repaired. In addition, the schemes described can be
twelve hours of retention time, subject to a varied substantially without adding greatly to the cost.
minimum working volume of 0.5 cubic meters) For example, to a standard pit privy with a PF, a vault
* Connection of the existing PF pit to the sullage could be added if housing density increases or the soil
tank with pipe 100 millimeters in diameter (the becomes clogged. Similarly, a composting toilet that
pit outlet "tee" junction should be located as near already has a watertight vault could be converted into
the top of the pit as technically feasible) an aquaprivy or PF toilet with a vault.
* Connection of the sullage tank to the street sewer As shown in figure 9-5, the initial sanitation facility
(the invert of the tank outlet should be a nominal (a) would consist of a VIP latrine with a concrete
3 centimeters below that of the inlet from the PF squatting slab and concrete block superstructure. An
pit to prevent sullage from flowing into the PF pit) actual facility of this kind in an East African city was
or to the soakaway. used as the basis for the costs shown. Its unlined pit is
If the existing PF pit has sufficient infiltration about 5.5 meters deep and I meter square, and the
capacity, there will be little or no flow from the pit to normal filling time is ten years. Its initial construction
the sullage tank. This does not matter-in fact, it will cost is $108, of which the superstructure accounts for
improve the functioning of the soakaway. But as the
infiltration capacity falls-and especially if cistern- In year 11 the community water system is upgraded
from wells or standpipes to yard hydrants, and the dry
fhe ptile are istalledted fo wi ease, and latrine is converted to a PF latrine (b) by digging a new
the it wll at asa seled r seiseaed frst soakage pit near the superstructure and replacing the
compartment of a two-stage septic tank. It is essential old squatting plate with a bowl and inverted siphon.
that the sullage tank (the second compartment of the
two-stage septic tank) is provided; otherwise, the The old pit is filled in prior to placement of the new
small-bore flat sewers (or the soakaway) will become squatting plate. For costing purposes, it is assumed
blocked. that the accumulated sludge would be removed from
the new pit at five-year intervals and composted.3 The
costs of trucks, land, and equipment for the compost-
Vault toilets ing facility are therefore included in year 15, and the
The system ofvalttiletsandacuumttrucks are replaced at five-year intervals thereafter.
Thed system cofmvalt tilets andas. vecacuu trevaucs i The operating and maintenance costs incurred in years
usedmos comonl in rba aras. ecase te vult 11-20 also included the cost of water for flushing the
satisfactorily stores the excreta and PF water and has a
PF latrine, which was calculated as 10 liters per capita
water seal, no upgrading is necessary for excreta
disposal. As the water supply service improves to a daily for six persons at $0.35 per cubic meter.
house c c ,In year 21 the third stage of scheme I would begin,
house~ ~ conetin hoee,swr.rohrsial when the water service is upgraded to house connec-
arrangements for sullage disposal may be desirable. If tien and a larvoue of upgage te has tonbe
sewers are installed, the vault toilet may be readily do
converted to a sewered PF toilet by connecting the isposed of. At this point a new lined pit would be dug
vault to the sewer system as described above. and the existing bowl and siphon would be connected
to it. An overflow pipe would connect the pit to a
newly constructed small-bore sewer system (c). This
upgrading would permit the use of cistern-flush toilets
Sample Staged Solutions if desired by the users. Annual collection of sludge
would be required from the smaller vault, and a
To demonstrate the feasibility of using a staged trickling filter plant would be constructed for treat-
sanitation system, four possible schemes or variations ment of the effluent.' The combined flushing water
are illustrated in figure 9-5, and comparative eco- and sullage flow from year 21 onwards is taken to be
nomic costs are presented for each. The last scheme, 175 liters per capita daily.
installation of a sewerage system with no preceding Comparative total economic costs, on a household
stages, is obviously not a sequence but is included in basis, were prepared for this scheme and for the three
the figure as a reference. Schemes 1-3 can be started variations-including the alternative of proceeding
with any stage and terminated at any point, depending immediately with the construction of a sewerage
on the desires of the users. For simplicity, it is assumed system (scheme 4).5 The total economic cost per
that each stage within a scheme will remain in service household of the three stages of scheme I over a thirty-
106 PROGRAM PLANNING AND DEVELOPMENT
Figure 9-5. Sample Sanritation Sequences
(costs in 1978 U.S. dollars)
Total present value
Item Year I Year 10 Year 20 / Year 30 economic cost
per household
over 30-year period
a .b r
Scheme I
Construction cost 108 65 9(5 354
a c
Scheme 2
Construction cost 108 915 1 . lI
Scheme 3
Construction cost 96(l 1.519
d
Scheme 4
Construction cost 978 3.00i0
a VIP latrine.
b PF toilet with soakawav.
C PF toilet with small-bore sewer (with optional bowl and seat).
d Conventional sewerage.
PROJECT DEVELOPMENT 107
year period (in 1978 prices) is $354, which includes sewerage. This is not because conventional sewerage
the salvage value of the sewerage system (assumed to systems should not be built (they are an excellent form
have a forty-year life). The second scheme shown in of sanitation for those who can afford them and who
figure 9-5 moves directly from the VIP latrine have plenty of water), but because they are not
(installed in year 1) to small-bore sewers (in year 11). necessary to provide a high standard of sanitation. The
The total cost per household over thirty years for sewered PF system (which can include a low-volume,
scheme 2 is $1,1 1 1, or more than three times that of cistern-flush toilet for users' convenience) yields an
the preceding three-stage alternative. The third equally high standard of service and has two major
alternative (scheme 3) is simply the installation of a advantages over conventional sewerage: it is substan-
small-bore sewerage system in year 1. This would have tially cheaper, and it can be reached by the staged
a total cost of $1,519 per household over thirty years. improvement of several different sanitation technolo-
The final alternative (scheme 4), for comparison gies. Thus, planners of sanitation programs can
calculated in the same way and with data from the confidently select one of the low-cost technologies in
same city as the small-bore sewerage system, is the the knowledge that, as socioeconomic status and
immediate construction of a conventional sewerage sullage flows increase, it can be upgraded in a
system. A construction period of five years is assumed, predetermined sequence of incremental improvements
and the facility is assumed to be two-thirds utilized to an ultimate level of desired convenience. The
upon completion and fully utilized ten years after important fact for concerned planners to remember is
completion. Based on these assumptions, the total cost that sewers are required to dispose of sullage, not
per household over thirty years is $3,000, which excreta, and that the elimination or reduction of
includes the cost of water for flushing and all regular nonessential water use is thus the crucial element of an
operating and maintenance costs (as do the costs of the economic solution to sanitation problems. This is
other alternatives). It is nearly ten times as high as the particularly significant in developing countries, where
cost of the three-stage scheme I and almost twice that the increasing competition for investment funds often
of the one-stage sewered PF alternative shown as limits the amount of resources that can be allocated to
scheme 3. the water and sanitation sector.
Another alternative to these upgrading schemes
would be to move from the VIP latrine to a vault toilet
with vacuum-truck collection in year 11. Based on
costs from such a system in a city on the island of
Taiwan, the total cost per household over thirty years Notes to Chapter 9
would be $334. If in year 21 it was decided to convert
from vacuum collection to a small-bore sewerage
system (as described in the previous schemes), the 1. See Donald T. Lauria, Peter J. Kolsky, and Richard N.
total cost would increase to $411 per household. These Middleton, Appropriate Technologyfor Water Supply and Sanita-
costsare smmarzed i thefolloing abulaion:tion. vol. 9. Low-Cost Design of Water Distribution Systems
costs are summarized in the following tabulation: (Washington, D.C.: The World Bank, 1980).
Total economic cost 2. Sites-and-services projects generally provide streets, water
per household supply, sanitation, and other basic infrastructure for an urban area;
(U.S. dollars) loan funds are made available to potential residents who build their
vip-vault collection 334 own houses.
vip-vault collection-small-bore sewer 411 3. In some communities, sludge may be buried rather than
VIP Pr-small-bore sewer 354 composted.
vi|p-small-bore sewer 1 ,1 11
Small-bore sewer 1,519 4. This option is chosen for illustrative purposes because of
Conventional sewerage 3,000 available cost data from the same East African city.
5. This is the present value (assuming an opportunity cost of
As is shown in figure 9-5, none of the upgrading capital of 10 percent) of the thirty-year investment and mainte-
sequences discussed above leads to conventional nance cost streams.
10
A Concluding Note
IN A SPECIAL SESSION on November 10, 1980, the reexamination of technologies must, therefore, include
United Nations General Assembly declared the 1980s a review of their development, and efforts must be
the International Drinking Water Supply and Sanita- made to identify those traditional technologies which
tion Decade. The objectives of the Decade-as are no longer, or only rarely, used in industrialized
promulgated by the nations participating in the countries but which could be improved or adapted
United Nations Water Conference in Mar del Plata, elsewhere to provide the health benefits of sanitary
Argentina, in April 1977-are to provide an adequate disposal of waste at significantly reduced cost.
supply of safe water and facilities for the sanitary This study has identified and evaluated traditional
disposal of waste for all by 1990, if possible, or to technologies found in a variety of communities and
reach such goals as governments consider feasible. At countries around the world. Costs and benefits have
the General Assembly meeting, governments also been assessed and improvements suggested. A method
submitted national plans for the Decade that indicated of sequential improvement of sanitation has been
targets to be reached and described actions to be taken developed to permit a gradual increase in the level of
during the Decade. convenience from the pit privy to a flush toilet in steps
If the Decade is one of action, rather than words that keep pace with the users' ability to pay for them.
-and preparatory activities since 1977 by both Incremental costs are low because each step in the
governments and international organizations active in sequence makes use of previously built facilities. The
the sector suggest that serious efforts will be made to study further examines institutional and engineering
make the Decade a success-significant improve- aspects of sanitation systems and has provided detailed
ments can be effected in the provision of water supply recommendations on how to evaluate sanitation needs,
and sanitation services to the inhabitants of developing design and implement projects, and organize the
countries. The success of the Decade will depend necessary institutional and community support.
primarily on finding effective ways to bring service to In demonstrating the feasibility of using low-cost
the poor. Women and children, in particular, suffer technologies appropriate to the conditions in large and
most from a lack of these services because they can small communities of developing countries, this ap-
least afford them, nor can they afford to protect praisal can play a significant role in the implementa-
themselves from infection or to seek a cure for tion of the International Drinking Water Supply and
sanitation-related disease. Sanitation Decade. Similarly, companion volumes
The design of water supply and sanitation services addressing specific topics or reporting case studies
affordable by the poor initially requires a reexamina- provide the planner, engineer, and community worker
tion of existing technologies that emphasize conve- with detailed information on the design, implementa-
nience rather than health benefits. This emphasis on tion, and implications for health of sanitation projects.
convenience is not surprising, given that the greatest (See the list of publications in the World Bank series
progress in developing sanitation systems in the past, a on water supply and sanitation given in the preface.)
topic examined in this appraisal, occurred in Great Nevertheless, these publications are but a beginning in
Britain and the United States at a time when the the process of designing appropriate solutions to the
economies of these countries were most productive and pressing needs of the world's poor for water supply and
their populations could afford to pay for "luxury" sanitation. The next steps are equally important:
sanitation. Consequently, it also is not surprising to
find that these systems are too expensive for universal . Economic planners and officials responsible for
use in the developing world, where scarce resources the allocation of international funds must be in-
must be carefully allocated to satisfy basic needs. The formed of the availability of appropriate technol-
108
A CONCLUDING NOTE 109
ogies that permit the provision of services to many traditional technologies, the adaptation of ad-
more people for the same cost as conventional vanced technologies, and the development of
technologies provide services to fewer users. health education techniques so that water supply
* Engineers must learn to use these technologies and sanitation services may be extended at lowest
and seek the participation of behavioral scientists possible cost. For example, upflow anaerobic
and health educators to help in the design of filters may extend on-site disposal, or sullage
projects fully responsive to the needs of the users water discharge to drains, to many areas hereto-
and in the implementation of such projects with fore considered unsuitable for the on-site disposal
the affected communities' participation. of wastewater.
* Master plans for water supply and sanitation
should provide service standards (and technolo- The list above is, of course, incomplete. But, given
gies) that the different groups in the community imagination and the courage to examine and recom-
can afford and that include the possibility of mend the unconventional, low-cost solutions to prob-
adding future sequential improvements. Profes- lems of water supply and sanitation will be found. This
sionals developing water plans and projects should study represents an initial step in this creative process.
be recompensed for the work to be done rather It is the hope of the authors that it will stimulate
than on the basis of the cost of their proposed others to join the effort and, thus, to ensure the
solutions. International Drinking Water Supply and Sanitation
* Work must continue on the improvement of Decade's success.
Bibliography
THE WORD "PROCESSED" describes works that are repro- Downing, Paul B. The Economics of Urban Sewage Dis-
duced by mimeography, xerography, or by any means other posal. New York: Praeger, 1969.
than conventional typesetting and printing; such works may Elmendorf, Mary, and Patricia K. Buckles. Appropriate
not be cataloged or commonly available through libraries. Technology for Water Supply and Sanitation, vol. 5,
American Society of Civil Engineers. Wastewater Treat- Sociocultural Aspects of Water Supply and Excreta
ment Plant Design. Manual of Practice, no. 36. New Disposal. Washington, D.C.: The World Bank, 1980.
York: American Society of Civil Engineers, 1977. Elmendorf, Mary (ed.). Appropriate Technology for Water
Anders, W. "The Berlin Sewer Workers." Zeitschrift fuer Supply and Sanitation, vol. 8, Seven Case Studies of
Hygiene (1954), pp. 341-71. Rural and Urban Fringe Areas in Latin America. Wash-
Appleton, B. "Acid Test for Middle East Brain Drains." ington, D.C.: The World Bank, 1980.
New Civil Engineer (February 19, 1976), pp. 23-29. Eckaus, R. S. "The Factor Proportions Problems in Under-
.. . . ~~~~~~developed Areas." American Economic Review, vol. 45
Arlosoroff, Saul. "Tradition and Innovation in Water Use (Sepember 5. 539m654
and Reclamation." In Gunnerson and Kalbermatten (September 1955), pp. 539-65.
(eds.), Appropriate Technology in Water Supply and Fair, Gordon M., John C. Geyer, and Daniel A. Okun.
Waste Disposal, pp. 61-84. Water Purification and Wastewater: Treatment and Dis-
Assar, M. Guide to Sanitation in Natural Disasters. Ge- posal. New York: John Wiley and Sons, 1968.
neva: World Health Organization, 1971. Feachem, Richard G., and A. M. Cairncross. Small Excreta
Disposal Systems. Ross Bulletin, no. 8. London: Ross
Bardach, J. E., J. H. Ryther, and W. O. McLarney. Aqua- Institute Information and Advisory Service, Ross Institute
culture: The Farming and Husbandry of Freshwater and of Tropical Hygiene, 1978.
Marine Organisms. New York: John Wiley and Sons, ofe roicha Hg, D.D
1972. Feachem, Richard G., D. Duncan Mara, and Kenneth O.
Iwugo. Appropriate Technology for Water Supply and
Barnet, A., L. Pyle, and S. K. Subramanian. Biogas Tech- Sanitationrvol.a7, Aternative anitation echnologie
nology in the Third World. Ottawa: International Devel- Sanitation, vol. 7, Alternative Sanitation Technologies
opogyeint tesearThi Wonterld. Oa:n ailD - for Urban Areas in Africa. Washington, D.C.: The World
opment Research Center, 1978. Bank, 1980.
Blackmore, M., R. Boydell, N. Mbere, and P. Moselele.
"Low-Cost Sanitation Research Project: Interim Reports m
1-3 and Final Report." Gaborone, Botswana: Ministry of Mara. Water, Wastes, and Health in Hot Climates.
Local Government and Lands, 1976-78. Processed. Chichester, U.K.: John Wiley and Sons, 1977.
Central Public Health Engineering Research Institute. Feachem, Richard G., David T. Bradley, Hemda Garelick,
Health Status of Sewage Farm Workers. Technical Di- and D. Duncan Mara. Sanitation and Disease: Health
gest, no. 17. Nagpur, India, 1971. Processed. Aspects of Excreta and Wastewater Management. World
Bank Studies in Water Supply and Sanitation, no. 3.
Clar, Sott,andothrs. Disase isk ofOccuatinal Baltimore, Md.: Johns Hopkins University Press, forth-
Exposure to Sewage." Journal of the Environmental En- comn. '
gineering Division, American Society of Civil Engineers, commg.
vol. 102, no. FE2 (1976), pp. 375--88. _ . Appropriate Technology for Water Supply and
Cotteral, J. A., and D. P. Norris. "Septic Tank Systems." Sanitation, vol. 3, Health Aspects of Excreta and Sullage
Journal of the Sanitary Engineering Division, American Management-A State-of-the-Art Review. Washington,
Society of Civil Engineers, vol. 95, no. SA4 (1969), pp. D.C.: The World Bank, 1980.
715-46. Gloyna, E. F. Waste Stabilization Ponds. Monograph Se-
"Directory of Composting Systems.'" Compost Science/Util- ries, no. 60. Geneva: World Health Organization, 1975.
ization, vol. 20, no. 1 (1979), pp. 22-25. Gunnerson, Charles G., and John M. Kalbermatten. "Alter-
110
BIBLIOGRAPHY 111
native Approaches to Sanitation Technology." Paper pre- Sanitation, vol. 2, A Planner's Guide. Washington, D.C.:
sented at the International Association for Water Pollu- The World Bank, 1980.
tion Research conference, Stockholm, June 1978. Pro- _ . Appropriate Technology for Water Supply and
cessed. Sanitation, vol. 11, A Sanitation Field Manual. Washing-
__ (eds.). Appropriate Technology in Water Supply ton, D.C.: The World Bank, 1980.
and Waste Disposal. New York: American Society of Kennedy, C. "Induced Bias in Innovation." Economic Jour-
Civil Engineers, 1979. nal, vol. 74 (September 1964), pp. 541-47.
. (eds.). Appropriate Technology in Resource Con- Kilama, W., E. K. Simbeye, and U. Winblad. "Alternative
servation and Recovery. New York: American Society of Waste Disposal Methods, Tanzania, 1975-77: Final Re-
Civil Engineers, October 1979. port." Dar es Salaam: Tanzania National Scientific Re-
Hinghaugh, G. M. A. "Nightsoil Treatment (on Lagos search Council, 1978. Processed.
Island)." The Consulting Engineer, vol. 37, no. 9 (1973), Kuhlthau, Richard A. (ed.). Appropriate Technology for
pp. 47-48. Water Supply and Sanitation, vol. 6, Country Studies in
Hirsheleifer, Jack, James C. DeHaven, and Jerome W. Sanitation Alternatives. Washington, D.C.: The World
Milliman. Water Supply Economics, Technology, and Bank, 1980.
Policy. Chicago: University of Chicago Press, 1960. Kumpf, E. H. W., K. Mass, and H. Straub. Mull- und
Julius, DeAnne S. "The Economic Cost of Power Outages: Abfall-Beseitigung. Bielefeld: Erich Schmidt Verlag,
Theory and Applications to Jamaica." Public Utility Re- 1964-80.
search Papers. Washington, D.C.: The World Bank, En- Laak, R., K. Healey, and D. Hardistry. "Rational Basis for
ergy, Water, and Telecommunications Department, 1976. Septic Tank Design." Groundwater, vol. 12 (1974), pp.
Processed. 348-52.
____. "An Economic Perspective on Resource Recovery Lauria, Donald T., Peter J. Kolsky, and Richard N. Middle-
and Reuse Projects." In Appropriate Technology for ton. Appropriate Technologyfor Water Supply and Sani-
Resource Conservation and Recovery, Preprint 3787. tation, vol. 9, Design of Low-Cost Water Distribution
New York: American Society of Civil Engineers, 1980. Systems. Washington, D.C.: The World Bank, 1980.
-_____ . "An Economic Appraisal of Sanitation Alterna- Mara, D. Duncan. Sewage Treatment in Hot Climates.
tives."Progress in Water Technology, vol. 11, no. I Chichester, U.K.: John Wiley and Sons, 1976.
(1979), pp. 251-58. Marais, G. v. R. "Fecal Bacterial Kinetics in Stabilization
____. "Urban Waste as an Economic Good." In Pacey Ponds." Journal of the Environmental Engineering Divi-
(ed.), Sanitation in Developing Countries, pp. 194-200. sion, American Society of Civil Engineers, vol. 100, no.
Julius, DeAnne S., and J. B. Buky. "Assessment of the EEl (1974), pp. 119-93.
Economic Contribution of Water Resources to National Metcalf and Eddy, Inc. Wastewater Engineering: Collec-
Development." Proceedings of the 1979 Institution of tion, Treatment, and Disposal. 2d ed. New York:
Civil Engineers Conference, "Water Resources-A McGraw-Hill, 1975.
Changing Strategy." Reprinted in Natural Resources McGarry, Michael G. "Developing Country Sanitation,"
Forum, vol. 4. no. 2 (April 1980), pp. 212-19. Report to International Development Research Centre.
Julius, DeAnne S., and Jeremy J. Warford. "The Economic Ottawa, February 1975.
Evaluation and Financing of Sewerage Projects." In McGarry, Michael G., and J. Stainforth. Compost, Fertil-
Guidelines and Standards. Washington, D.C.: The World izer, and Biogas Production from Human and Farm
Bank, Transportation, Water, and Telecommunications Wastes in the People's Republic of China. Ottawa: Inter-
Department, February 1977. Processed. national Development Research Centre, 1978.
Kalbermatten, John M., and DeAnne S. Julius. "Intermedi- Mohanrao, G. J. "Waste Collection, Treatment, and Dis-
ate Service Levels in Sanitation Systems." In Gunnerson posal in India." Indian Journal of Environmental Health,
and Kalbermatten (eds.), Appropriate Technology in Wa- vol. 15, no. 3 (July 1973), pp. 222-35 (six table refer-
ter Supply and Waste Disposal, pp. 123-45. ences).
Kalbermatten, John M., DeAnne S. Julius, and Charles G. National Academy of Sciences. Making Aquatic Weeds Use-
Gunnerson. Appropriate Technology for Water Supply ful: Some Perspectives for Developing Countries. Wash-
and Sanitation, vol. 1, Technical and Economic Options. ington, D.C., 1976.
Washington, D.C.: The World Bank, 1980. _ . Methane Generation from Human, Animal, and
Kalbermatten, John M., DeAnne S. Julius, Charles G. Agricultural Wastes. Washington, D.C., 1977.
Gunnerson, and D. Duncan Mara. Appropriate Sanita- National Environmental Engineering Research Institute.
tion Alternatives: A Planning and Design Manual. World Night-soil Wheelbarrows. Technical Digest, no. 32. Nag-
Bank Studies in Water Supply and Sanitation, no. 2. pur, India, 1972. Processed.
Baltimore, Md.: Johns Hopkins University Press, forth- Okun, Daniel A., and G. Ponghis. Community Wastewater
coming. Collection and Disposal. Geneva: World Health Organi-
. Appropriate Technology for Water Supply and zation, 1975.
112 BIBLIOGRAPHY
Pacey, A. (ed). Sanitation in Developing Countries. Chich- Shuval, H. 1. "Parasitic Disease and Wastewater Irriga-
ester, U.K.: John Wiley and Sons, 1978. tion." In Pacey (ed.), Sanitation in Developing Countries,
Pahren, H., and W. Jakubowski (eds.). Wastewater Aero- pp. 210-14.
sols and Disease. Report no. USEPA-600/9-80-028. Wash- Shuval, H. I., Charles G. Gunnerson, and DeAnne S. Julius.
ington, D.C.: U.S. Environmental Protection Agency, Appropriate Technology for Water Supply and Sanita-
1980. Available from National Technical Information tion, vol. 10, Night-soil Composting. Washington, D.C.:
Service, Springfield, Va. 22161. The World Bank, 1980.
Pearson, H. "Toxic Effects of Inorganic Salt Build-up on Spangler, Charles. Appropriate Technology for Water Sup-
Microalgae in Zero- and Low-Flow Night-soil Treatment ply and Sanitation, vol. 12, Low-Cost Water Distribu-
Ponds." Washington, D.C.: The World Bank, Transporta- tion-A Field Manual. Washington, D.C.: The World
tion, Water, and Telecommunications Department, 1978. Bank, 1980.
Processed. Squire, Lyn, and Herman G. van der Tak. Economic Analy-
Pescod, M. B., and Daniel A. Okun (eds.). Water Supply sis of Projects. Baltimore, Md.: Johns Hopkins University
and Wastewater Disposal in Developing Countries, Pro- Press, 1975.
ceedings. Bangkok: Asian Institute of Technology, 1971. U.S. Environmental Protection Agency. 2 Water Quality
Processed. Criteria. Washington, D.C., 1973.
Pradt, L. A. "Some Recent Developments in Night-soil _ . Health Effects of Nitrates on Water. Report no.
Treatment (in Japan)." Water Research, vol. 5 (1971), USEPA-600/1-77-30. Washington, D.C., 1977. Available
pp. 507-21. from National Technical Information Service, Spring-
Raman, V. Sanitation Facilities for Slums and Rural Ar- field, Va., 22161.
eas. Nagpur, India: National Environmental Engineering U.S. Public Health Service. Manual of Septic Tank Prac-
Research Institute, 1975. Processed. tice. USPHS Publication no. 526; revised 1967. Washing-
Raman, V., and N. Chakludor. "Upflow Filters for Septic ton, D.C.: U.S. Government Printing Office, 1972.
Tank Effluents." Journal of the Water Pollution Control _ . Sewage Stabilization Ponds in the Dakotas. Wash-
Federation, vol. 44, no. 8, pp. 1552-60. ington, D.C.: U.S. Government Printing Office, 1957.
Rybczynski, Witold, Chongrak Polprasert, and Michael G. Wagner, E. G., and J. N. Lanoix. Excreta Disposal for
McGarry. Low-Cost Technology Options for Sanitation: Rural Areas and Small Communities. Monograph Series,
A State-of-the-Art Review and Annotated Bibliography. no. 39. Geneva: World Health Organization, 1958.
A joint International Development Research Centre/ Warford, Jeremy J. "The Multiple Objectives of Water
World Bank publication. IDRC-102elAppropriate Tech- Rate Policy in Less Developed Countries." Water Supply
nology for Water Supply and Sanitation, vol. 4. Ottawa: and Management (November 1977), pp. 335-42.
IDRC, 1978. . "Water Rates in Developing Countries." Journal of
Saunders, Robert J., and Jeremy J. Warford. Village Water the American Water Works Association (April 1979), pp.
Supply. Baltimore, Md.: Johns Hopkins University Press, 199-203.
1976. Warford, Jeremy J., and DeAnne S. Julius. "Water Supply
Saunders, Robert J., Jeremy J. Warford, and P. C. Mann. and Sewerage Service Standards in LDCs." Paper pre-
Alternative Concepts of Marginal Costfor Public Utility sented at the American Society of Planning Officials
Pricing: Problems of Application in the Water Supply Conference, San Diego, April 1977. Processed.
Sector. World Bank Staff Working Paper, no. 259. Wash- White, A. U., and G. F. White. "Behavioral Factors in
ington, D.C., 1977. Selection of Technologies." In Gunnerson and Kalbermat-
Shaw, V. A. "A System for the Treatment of Night-soil and ten (eds.), Appropriate Technology in Water Supply and
Conserving-tank Effluent in Stabilization Ponds." Public Waste Disposal.
Health Johannesburg, vol. 63 (1963), pp. 17-22. In Afri- White, G. F., D. J. Bradley, and A. U. White. Drawers of
kaans; English translation available as CSIR Reprint Water: Domestic Water Use in East Africa. Chicago:
RW166 from the National Institute for Water Research, University of Chicago Press, 1972.
P. 0. Box 395, Pretoria, South Africa. Winblad, U., W. Kilama, and K. Tortensson. Sanitation
Shipman, H., and others. "Measurement of the Health without Water. Stockholm: Swedisfi International Devel-
Benefits of Investment in Water Supply." Public Utility opment Authority, 1978.
Report, no. 20. Washington, D. C.: The World Bank, Winneberger, J. H. Manual of Graywater Treatment Prac-
Transportation, Water, and Telecommunications Depart- tice. Ann Arbor, Michigan: Ann Arbor Science Publish-
ment, January 1976. Processed. ers, 1974.
Index
Page nsumbers in italics indicate maps, tables, or illustrations.
Aesthetics, importance of, 65 Cartage systems, 44; annual vacuum costs Consumer preferences. See Community
Affordability, 64, 99 per household for, 59; limiting factor views and preferences
Algorithms, 99, 100, 102, 103 in, 39: sewerage vs. 60; upgrading, 59. Contamination of water, 95
Alternative sanitation technologies: ben- See also Vault and vacuum-truck sys- Continuous composting latrines and toi-
efit levels of, 5(0-51 community pref- tem lets. 13, 15
erences for, 95; comparing, 50, 52, 53; Cattle, tapeworms and, 73 Conversion factors, price and foreign ex-
costs of, 50. 51, 53, 54-61, 63; failures Children: deaths of (from disease and change, 66nll
of. 5; identifying, 5; lack of design ex- malnutrition), 3; excreta disposal and, Cost-benefit ratio. See Benefit-cost ratios
perience with. 86; matrix ranking of, 70; ROECs and, 12: schistosomiasis in. Costing: comparative, 50; economic, 51:
50; most common, 11: need for, 4; in 68; as sources of infection, 70 life-cycle. 5; principles of, 51-52. See
urban settings, 97-98. See also Sanita- China, sanitation technology in. 75 also Costs
tion program planning; Sanitation sys- Choice of technology: factors affecting. Costs: anomalies of, 66nl2; average in-
tems 18, 39, 42, 44, 47, 50, initial investment cremental (AIC). 53: capital, 54: case
Anal cleansing materials: for aquaprivies. and, 57: use of algorithms in, 49; use data for, 59; of conventional sanitation.
16; choice of technology and. 42; for PF of matrix of characteristics in, 49. See 97: conversion factors and input, 56;
latrines, 15 also Alternative sanitary technologies; economies of scale and. 52. 53: field
Ancvlostorma duodenale, 33 Appropriate technology: Sanitation studies and, 54-59: historical. 51: in-
Appliances, low-water-use, 66nlO program planning cremental, 51; input and conversion. 5:
Appropriate technology: consulting firms Cholera. 30 investment and recurrent. 56-57; per
and choice of, 8n9; defined, 5: identi- Cistern-flush toilets. 99 capita. 52. 53: real resource, 52. 60:
fication of, 4, 5. 7-8: incentives for im- Climate, 18 22, 23, 24 recurrent. 54, 56-57; subsidization of.
plementing, 86-88: obstacles to imple- Clonorchis sinensis. 45 63: sullage wastes and, 53: total annual
menting, 85-86. See also Alternative Cockroaches, 68, 72. 73 per household, 55: upgrading. 105, 117:
sanitation technology: Choice of tech- Communal sanitation systems, 13, 17, 100; of various technologies. 55, 57-59: 64-
nology investment costs of, 64 61: water, 52. 56-57. See also Economic
Aquaprivies. 13. 14. 15-16, 61: self-top- Community involvement, 79, 81, 88. 91. costs: Financial costs: Sanitation pro-
ping (or sullage), 16, 44 94-95; objectives of, 93; rural, 98; scope gram planning: TACH
Aridity, 18, 25, 26, 27 of. 93-94; steps in, 96; urban. 97, 98 Crops: fertilization of, 44: survival of
Ascaris eggs, survival of, 73, 74, 75 Community views and preferences, 4, 86. pathogens on, 75
Average incremental cost (AIC). See Costs, 88: costs and. 7; credibility gap and. 79: Culex pipiens, 37. 68
average incremental (AIC) design and, 65; determining, 94-95; on Cultural aspects of sanitation. See Com-
latrine and toilet facilities, 78; on water munity views and preferences
Bacteria, 71. See also Infections supply abundance and proximity, 78.
BARC thermophilic composting system, 43, See also Incentives and motivation Data: gathering, 77. 87. 95; use of case,
46 Community water and sanitation systems, 59. See also Surveys
Batch composting latrines and toilets. 13; 16-18; bucket latrines and. 14, 16-17; Decisionmaking, algorithms as guidcs for.
DVC as most common type of, 15 investment and recurrent costs of, 57; 99
Beltsville Agricultural Research Center users' view about. 78; vault toilets and, Defecating practices, 78. 79
(BARC), 46 14, 17 Demand analvsis. 86
Benefit-cost ratio, 50: divergence over Comparative costing. See Costing Demand forecast, 65n8
time, 52 Complementary investments, 39 Design. importance of, 65, 77, 78. 79. 81
Biochemical oxygen demand (BOD), 43. Composting: aerobic, 43: anaerobic, 15; Desludging. 16
47 BARC system, 43, 46: carbon-nitrogen Diphyllobothrium latum, 73
Biogas, 44, 46. 61-62 ratio for, 15; health aspects of, 73, 75; Diseases, 18, 30, 31, 32, 33, 34. 35. 36.
Birds, tapeworm transmission and, 73 latrines and toilets, 13. 14, 15: moisture 37
Botswana. 61 control and, 15; temperature and, 15; Double-vault composting (DVC) toilet 14,
Bucket latrines, 13, 14, 16-17 thermophilic, 46 15. 44, 61, 100, 101
Conservation, 79. See also Reclamation Ducks and fish production, 45
Capital: opportunity cost of, 51; price of, and reuse
51: shadow price of, 66n23 Construction by homeowners, 39, 42, 87 Economic costs: financial costs vs., 8n8,
Carbon-nitrogen ratios, composting and, Consulting firms and selection of appro- 86: per household for upgrading, 1(07;
15 priate technology, 8n9, 87, 97 purpose of deriving, 63.
113
114 INDEX
Educational programs, 42; supplementing Land use, 18, 38, 39, 40 Prices: convcrsion factors and. 66n Il; real
sanitation improvements. 76. See also Latrines, influence of floor color on use costs and. 51; used to value costs, 51
Training of, 65. See also name of specific latrine Productivity. potential, 28
Emergencies. arrangements for, 95 type Protozoa. 71
Engineers: awareness of range of sanita- Laundry facilities, 17
tion technology and, 85; reeducation of, Least-cost solution, 51 Questionnaires. See Surveys
4 Lending agencies, 63, 85, 87
Exchange visits, 95 Liver fluke, 45 Reclamation and reuse. 39. 79; agricul-
Excreta disposal programs, 4. See also Loans, 64 tural. 44. 45. 62-63; aquacultural. 63;
Sanitation projects Local customs, 5 benefits from. 61-63, 66n2(): costs and.
Excreta disposal systems, 100. See also London School of Hvgiene and Tropical 61: health effects and. 73. 75. See also
Sanitation systems Medicine, 67 Biogas
Excreted infections, 4, 71, 72; environ- Low-income rental units, floor plans for, Reed Odorless Earth Closet (ROfC). 13.
mental classification of, 70-73; spread 40 44, 61, 10(i. 101: advantage of. 12; dis-
by insects, 73 Maintenance: continuous composters and advantage of. 12: odor and flv nui-
importance of, 15; ensuring, 81; prob- sances and. 11. 12; upgrading. 13. 39.
Feasibility studies 6, 7, 87 lems with, 42; social preferences and, 1l)1
Fertilization, 44 7 Research needs, future. 47
Filariasis, 68, 73 Malacca. 53, 60 Resource rccovery. See Reclamation and
Filter plants, 42, 105 Management skills, cost and, 56 reuse
Financial costs: difficulty in developing, Master plan, 97-98 Reuse. See Reclamation and reuse
63; economic costs vs.; 8n8. 86; for least- Methane production. See Biogas Ross Institutc of Tropical Hygiene. 67
cost solutions, 7; real resource costs vs., Methemoglobinemia, 68
60; user income and, 7; Models (construction), 81 Salmonella. 68-69
Fish culture using night soil, 44. 45, 75 Models (economic) 53 Sanitation agency, ingredients of, 89-911
Fishponds, design of, 45A46 Mosquitoes: breeding of (in waste stabi- Sanitation facilities: constraints on pro-
Flatworms, See Trematodes lization ponds), 43; filafiasis and, 73 visfon of. 4: in neighborrna areas. 99:
Flies, 68; pit latrines and, 11; as vectors sullage and, 68; as vectors of excreted for tha poor, 93 for rural arecas. 93
of excreted infections, 72, 73; viP la- infections, 73. Sanltathon 7Iprovmentsa effects of (on
trines and, 11; water seals and, 65 Motivation. See Incentives and motiva- health)q 7n: importanc. of sequentialo
Food: preparation of, 72, 75; risk of in- tion 5; sequences for. 1(11. 104. 105. See also
fection from, 75 Municipal services in developing coun- Upgrading
tries, 4 Sanitation program planning: educational
Gaborone, 53-54, 61 programs and. 42; feasibility studies for.
Necator americanus, 34 6; institutional responsibilities for. 92:
Helminths, 71; intermediate aquatic hosts Night soil: disposal of. 17; facilities for statistical approach to. 53: traditional
and, 70, 73; transmitted by excreta, 69; treatment of, 39; health aspects of approach to, 7- use of surveys and ques-
transmitted by soil, 72 digestion techniques, 73, 74. 75; man- tionnaircs ini 77. 78 79. See also Choice
Higashi-Kurume (Japan), 60 agement schemes for (examples), 46- of technolo_s,y ( osts
Household sanitation systems, 11-13, 13, 47, 48; treatment alternatives. 42-43 Sanitation proicets: behavioral science and
14, 15-16; influences on costs of, 65; Odor: aquaprivies and, 16: bucket la- design of, 79-82; community partici-
investments costs of, 64; users' views trines and. 17; pit latrines and, I I; vip pation in. 79. 81 SS. 90(: failure of. 77.
on, 78. See also name of specific system latrines and, I l; water seals and. 65 82, 89: moNeTiment su.pport for. 89. 90:
Housing density, 39 Off-site exereta disposal systems. 13, 14, incenti%cs and motivation for, 78-79:
39 institutional rvquirements for. 89-92:
Immunity, 69-70, 71 On-site excreta disposal systems, 110( measuriiw hnefits of .5(, 67: m,onitor-
Incentives and motivation, 78-79, 86-88 Overhung latrine, 13 ino. 82 or. Siniz tion for. 89-9s c pro-
motion of, 81: ruirzil. 98: sociocultural
Individual preferences. See Community Pathogens: in compost. 15, 73. in feces dimensions of desion of. 8(): survess and
views and preferencesI
Infections: bacterial, 70-73; control and sewerage. 68-69: host response to. questionnaircs in, 77; types of. 97-99:
measures for, 70; insect transmission of, 69; hosts of. 7(0: latencv of. 69; most urban. 97 98. See albo SanitIation pro-
73;sures involvingexre, a 3,; 6ms 0 witlow o resistant. 73; persistence of. 69, re- gram planningo Sa nitation svstems
infective dose, 70 moval of. 42. 43; spread of. 68. survival Sanitation scrvices. 8: constrainlts on (in
Infrastructure, 98, 99 times of. 73. 74, 75 developing countries). 4; cost of con-
Infraseructs:aquaprivies and. 16; bucketa Personal hvgiene, 88; effects of (on health). ventionl, 3: for enltire community. 97;
Insects: aquaprivies and, 16; bucket la- 75 'orpanizationI for, S9-92. paymcnt- for,
trines and. 17; excreta and, 68. See also orai Onfr899;pyetfr
specific kind, of; iexcrta and, 68.Seealso Physical environment. 18, 39 87, 88n'7 911 solutioni to (in developing
Institutiokna cofnstraints, 42Pigs. See Swine countries). 4. urban and rural. 97-99
International constraints, Researh Pit latrines, 13; as most common tech- Sanitation svstems, 42. 44; comparative
International Development Research nology, I; population densitv and, 13. costs of 54-59: cost case data (specific
Centre, 54; bibliography on sanitation 39; suitability of. 13; upgrading of. 13 locations) 59-63: economics of scale
technologies, 85; experimental latrine Planning. See Sanitation program plan- and, 527. :g encric classification of. 14:
program of (Botswana), 60-61 ning inflexihilits of laroe scale, 53; low-cost.
International Drinking Water Supply and Ponds. See Waste stabilization ponds 47. 88: matjor benefits of. 5(). 61: per
Sanitation Decade, 3, 4, 88 Population densitv. 13. 39 capita costs of sewerage. 52; per house-
Interviews, 94 Pour-flush (PF) latrines and toilets, 13. 14. hold costs of sewcraee. 59; water supply
Irrigaton, infection from, 75 15. 44. 10(), 106; upgrading. 39, 1()1, levels and options in 39. 41. Scc a/so
Israel, 75 105 AlternatisNe sanitation tcchnoloeics:
Precipitation (meteorological). 18. 21. 22 Sanitation program planning: Sanita-
Korea, 61, 62 Preferences. See Community views and tion projects: name of sp)ecific ivpie of
Kyoto (Japan), 46-47, 48, 60 preferences srsteom
INDEX 115
Schistosoma haematobium, 31 Swine, 45, 75, 79; tapeworms and, 73 pit latrines, 13; from ROEC toilets. 13,
Schistosoma japonicum, 31 Synthetic studies, 53 39. 101: samole solutions for staged.
Schistosoma mansoni, 32 Io5, 106, 107; from vault toilets, 17,
Schistosomiasis, 68, 73 TACH (Total annual cost per household): 101, 105; from viP toilets, 13, 39, 101;
Self-help construction, 39, 42, 87 difference between actual cash expend- to water-seal units, 39; water supply
Seng, Ng Kin, 66n19 ituresand, 54; investmentcostsand, 57. service and, 39
Septic tanks, 13, 14, 16, 44; with drainage 57; of on-site systems and sewerage in Urban sanitary facilities: demand for, 86;
fields, 99; three-stage, 44, 100, 101 Gaborone, 61; of public night-soil col- sewers as, 18; urban growth predictions
Sewerage, 17-18, 44, 48, 61; annual costs lection system in Taiwan, 63; recurrent and, 53
per household, 59; appropriateness of, costs and, 57, 57; separation of (into
107; bias in favor of, 85; cartage vs., functional components), 58-59; of sew- Vault latrines and toilets 13 14 17 39
60; high cost of, 97, 107; historical de- erage and vacuum-truck cartage in Ma- 17 ,
velopment of. 4; in industrialized coun- lacca, 60; for ten technologies, 55; use 44. 100
tries, 3; low-cost alternatives to, 5; of (in comparing technologies), 54 Vault and vacuum-truck system (exam-
manage'ment schemes for (examples), Taenia saginata, 35, 71, 73 ple), 46-47
46-47, 48; treatment alternatives, 42- Taenia solium, 36, 71, 73 Ventilated mproved double-pit (VIDP) la-
43 Taiwan, 61 62, 63 trmes, 11
Sewered facilities (PF toilets, septic tanks, Tapeworms, 36, 36, 71, 72, 73 Ventilated improved pit (VIP) latrines, 11,
aquaprivies), 44, 100; advantages over Tariffs, 87, 88n2, 90 3, 14, 44, , , , 5, up-
conventional sewerage, 107 Technical support: arrangements for, 90, graded to PF toilets, 13, 105
Sewer systems, 13; conventional vs. small- 94; by periodic visits of technicians, 95 Ventilatcon sacks, 65
bore, 18; failure of, 18; maintenance of, Technological choice. See Alternative Virueo cholera, 68
4; materials for, 18; per capita construc- sanitation technologies; Appropriate Viruses, 71; control of infections caused
tion costs of, 52; slope needed, 18; small technology; Choice of technology; San- by, 71-72; survival of enteric, 73, 74,
bore, 105; treatment works for, 39 itation program planning
Shadow values, 51 Technologies: cost comparisons and, 54-
Showers, 17 61; demand curve for, 86; diffusion of, Waste disposal, waterborne, 4
Sludge: batch digestion of, 42; treatment 80-81; lack of awareness of range of, Waste stabilization ponds, 43; evaluation
of, 42-43. See also Desludging; Sew- 85; least-cost solutions and, 7; low-cost, of health aspects of, 73, 75
erage 54-55, 107; modification for adoption Water: amount used to flush toilets, 65n6,
Snails: eradication programs for (in China), of, 81-82; need for frequent reassess- 66nl6; health and, 67, 68; influence of
75; trematodes and, 69; in waste sta- ment of, 89; selection of, 5, 7, 80, 98, cost of, 56-57; significance of reducing
bilization ponds, 43, 45 99-101. See also Alternative sanitation nonessential use of, 107; users' percep-
Soils, 18, 29; survival of pathogens in, 75 technologies; Appropriate technology; tions about, 78; volume needed of safe,
Spray irrigation, possible infection from, Choice of technology; name of specific 75
75 technology. 22, 23, 24 Waterborne waste disposal. See Sewerage
Statistical studies, 53 Temperatures: in compost, 15; winter, 18, Water and sanitation agency, 89-90
Storm-water drains, 53 19. 20, 22 Water-saving appliances and septic tanks,
Study communities, 12, 13 Training: for community workers, 99; for 99
Subsidization of costs, 63 staff, 90, 95. See also Educational pro- Water seal: in converting ROEC to PF toi-
Sullage: costs and treatment of, 53; de- grams let, 101; in converting viP to PF toilet,
fined, 49n4; disposal of, 43-44, 67, 101; Trematodes and snails, 69 101; maintenance of, 16; odors and, 65
as health hazard, 44, 67, 68; and sew- Water service levels, 39; sanitation op-
ered PF system, 100, 105 United Nations Water Conference (Mar tions and, 41, 99, 101, 104; for selected
Superstructures (latrine), moving of, 78 del Plata. Argentina. 1977), 3 study communities, 12; users' percep-
Surveys, 80, 87; interviewers for making, Upgrading, 5, 47; from aquaprivy system, tions about. 78, 101
94; interviews to determine local atti- 16; from bucket latrine, 17; to cistern- Water supply projects and services, or-
tudes, 94; methods, 77; questionnaires. flush toilet, 101; from DVC toilets, 39. ganization for, 89-92
79, 94; results of. 78-79 101; from PF toilets, 39, 101, 105; from Wells, distance of (from pit latrines), 13
The full range of World Bank publications, both free and for sale,
is described in the Catalog of World Bank Publications; the continuing
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stracts of Current Studies. Both booklets are updated annually; the
most recent edition of each is available without charge from the Pub-
lications Unit, World Bank, 1818 H Street, N.W., Washington, D.C.
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John. M. Kalbermatten is senior adviser for water and wastes and
Charles G. Gunnerson is senior project officer in the Transportation
and Water Department of the World Bank. DeAnne S. Julius is acting
economic adviser for the Energy Department of the World Bank.
A World Bank Publication
The United Nations has designated the 1980s as the International Drinking
Water Supply and Sanitation Decade. Its goal is to provide two of the most
fundamental human needs-safe water and sanitary disposal of human
wastes-to all people.
To help usher in this important period of international research and coopera-
tion, the World Bank is publishing two volumes on appropriate technology for
water supply and waste disposal systems in developing countries. Since 1976,
Bank staff and researchers from various countries have been analyzing the
economic, environmental, health, and sociological effects of various
technologies to identify the most appropriate systems for the needs and
resources of different areas. The research has included field investigations in
nineteen countries.
Since the technology for supplying water is better understood, the emphasis in
these volumes is on sanitation and waste reclamation technologies, their
contributions to better health, and how they are affected by water service
levels and the ability and willingness of communities to pay for the systems.
This volume summarizes the technical, economic, environmental, health, and
sociocultural findings of the World Bank's research program on appropriate
sanitation alternatives and then discusses the aspects of program planning that
are necessary to implement these findings. It is directed primarily toward
planning officials and sector policy advisers for developing countries.
The most important finding is that there are many different kinds of
technology that can be safely and cheaply used on a wide scale. Sanitation
sequences-step-by-step improvements in sanitation technology that can
build on each other as a community can afford to upgrade its system-are also
designed and costed. In addition, a new and promising approach is presented
to the problem of linking potential benefits to health with improvements in
environmental sanitation.
The Johns Hopkins University Press Baltimore and London
ISBN 0-8018-2578-4