from EVIDENCE to POLICY Learning what works for better programs and policies April 2020 BANGLADESH: Can automated chlorination at shared water taps reduce disease in urban slums? Safe drinking water is essential for healthy human development on the expense and responsibility of treating their own drink- and survival, but millions of poor people in low-income coun- ing water. tries only have access to contaminated drinking water. For chil- Another less-explored option is treating water at the shared dren, the problem is particularly dangerous and deadly, with taps and pumps where most poor city dwellers get their water, WATER AND SANITATION diarrheal diseases like typhoid and cholera responsible for ap- but finding a reliable and cost-effective system has been a chal- proximately 800,000 child deaths each year. lenge in many contexts. Yet addressing the problem of unsafe drinking water is dif- As part of this effort, the World Bank’s Strategic Impact ficult and complex, especially in large and growing city slums. Evaluation Fund (SIEF) supported an impact evaluation of Poor urban areas often have inadequate infrastructure, and in- a novel water treatment technology designed to help reduce stalling traditional water and sanitation infrastructure can be the burden of water-related illness. The research team devel- prohibitively expensive. Even where water treatment plants ex- oped and implemented a system that automatically chlorinated ist and function, drinking water is often re-contaminated by water at public taps and shared hand pumps. The evaluation sewage as it travels in unpressurized pipes to water collection found that the chlorination method significantly improved points in different parts of the city. Given these challenges, water quality and reduced child diarrhea, providing strong evi- there has been a big push to get families to treat their own water dence that drinking water quality affects children’s health and by filtering or chlorinating it at home. However, this approach that improvements in drinking water quality should be a fo- hasn’t been very successful either. Home treatment requires cus of policy, not just the quantity of water provided. Further, that people remember to buy, measure, and use the chlorine, these results hold promise for achieving global progress towards and the poorest families, who are at highest risk of their chil- the Sustainable Development Goal of attaining universal access dren dying of diarrhea, typically do not have the means to take to safe and affordable drinking water. Context In Dhaka, Bangladesh, more than 20 percent of the city’s 15 home disinfection technologies such as chlorine products and million residents live in slums and almost all rely on shared taps filters, but these efforts have generally not succeeded. One or handpumps for water. Because of water shortages in the city, study found that even when chlorine was provided for free, water is not always available; it is sent to different parts of the only a small proportion of people actually used it. Dhaka’s city at different times during the day. Because the water system public water utility company had not considered installing dis- isn’t fully pressurized at all times, contamination and sewage infecting solutions at shared community taps before because seep into the water. Before this project began, 87 percent of cost-effective technologies weren’t available. But the approach taps in the study’s Dhaka neighborhood were contaminated held promise: getting treating water at the taps would be auto- with E. coli, and 50 percent of taps in nearby Tongi – the other mated, as people filling containers with water would not have study site – contained the fecal indicator bacteria. to do anything to make it clean. In Bangladesh, there has been a big push to market in- This policy note is based on: Pickering, Amy J., Yoshika Crider, Sonia Sultana, Jenna Swarthout, Frederick GB Goddard, Syed Anjerul Islam, Shreyan Sen, Raga Ayyagari, and Stephen P. Luby. “Effect of in-line drinking water chlorination at the point of collection on child diarrhoea in urban Bangladesh: a double-blind, cluster-randomised controlled trial.” The Lancet Global Health 7, no. 9 (2019): e1247-e1256. Evaluation although the research team did have an engineer working In Bangladesh… full time on the project to ensure that the devices functioned • 34.6 percent of people have access to safe drinking water. properly. Unlike home treatment or other systems that require • 99 million people drink water that is contaminated with people to add in chlorine themselves, the technology studied microbes. here was “passive” – requiring no additional effort or action on • 41.7 percent of people’s water source is contaminated the part of the end user. with fecal bacteria. A local partner organization conducted a one-hour edu- • 61 percent is infected with fecal bacteria by the time it is consumed. cation meeting with each household before the pumps were Source UNICEF (2018) equipped with the device. Follow-up promotional visits were WATER AND SANITATION held every two months for the first six months, then once every Researchers conducted a clustered randomized controlled trial four months for the next eight months. The partner was re- in urban Bangladesh to evaluate how an automated chlorina- sponsible for resupplying chlorine to the dispenser every week. tion system, based at water collection points, affects the qual- Researchers collected data from households and at the wa- ity of water stored in homes and child health. The study took ter collection points every two months for 14 months. After place in two sites: a low-income comwmunity within the city 14 months, the team compared outcomes between house- of Dhaka and a low-income community known as Tongi on holds linked to shared water points with chlorine dispensers the outskirts of the city. and households linked to shared water points that received the The research team first enrolled 920 eligible households, vitamin C. The primary outcome of interest was caregiver- with a total of 1,036 children younger than 5 years at base- reported child diarrhea (based on the World Health Organi- line. After the initial baseline survey in July-November 2015, zation’s definition of more than three loose or watery stools researchers randomly assigned 100 shared water collection in a 24-hour period). Researchers also tracked impacts on points with water storage tanks to either a treatment group, another measure of diarrhea (that is, how caregivers defined which received the chlorine treatment, or to an active control it), child weight-for-age, child height-for-age, acute respiratory group, which received vitamin C dosers that looked visually illness, illness-related health-care expenditures, water quality, identical to the chlorine dispensers. The research team installed and chlorine in households’ stored drinking water. They also the chlorine dispensers in storage tanks connected to manual collected additional information from enrolled households on handpumps in the treatment group, and installed the vitamin demographics, education, employment, dwellings, and assets. C dosers in the control group. The evaluation was “double-blinded,” meaning neither the study field staff nor the participants knew which study group the communities were a part of. This design reduced the likeli- hood of bias in the follow-up survey, when participants may have reported what they thought researchers wanted to hear or what they – or researchers – thought should have happened. The system used in this study, the Aquatabs Flo (manu- factured by Medentech, Inc) automatically doses chlorine into water as it flows through the device into a water storage tank. Researchers picked the device after implementing two pilot studies in Dhaka that tested various low-cost products that au- tomatically chlorinate water. The Aquatabs Flo device has no moving parts and does not require electricity to operate, Source: Standford University Findings Children living in treatment communities experi- in the Tongi group. The reasons for this aren’t completely enced a notable reduction in diarrheal disease as a clear, but researchers have a couple of theories. Although result of the automated chlorine dispensers. both study sites had intermittently supplied water, water quality in Dhaka was poorer at baseline than in Tongi. An- Based on caregiver reports, 7.5 percent of children in the other potential explanation for difference across study sites treatment group had experienced three bouts of diarrhea in a could come from the fact that the different areas may have 24-hour period in the last week (the WHO definition) com- different pathogens; chlorination is not effective against pared to 10 percent of children in the control group––a dif- certain parasites such as cryptosporidium, for example. ference that corresponds to a statistically significant reduc- tion of 23 percent. When caregivers were free to define what they thought constituted a diarrheal episode, the dispensers also led to a similar reduction in disease. The device was reliable and effective at chlorinat- ing the water, which led to a large reduction in fe- cal bacteria in the water. The research team detected chlorine in the water treatment group taps 83 percent of the time, as opposed to zero per- cent of the time in the control group, revealing the device was reliable in treating the water. Looking at home drink- ing water, researchers found that 45 percent of households in the treatment group had chlorine in stored drinking wa- Source: GMB Akash ter compared to no households the control group. (It is There were other indications that children were worth noting that treatment households – though blinded sick less often as a result of the chlorination, but to whether their water was treated with chlorine or just the improvements in water quality did not trans- vitamic C – were slightly less likely to treat their water at late into improved child growth. home.) Importantly, the device led to a dramatic decrease in E. Caregivers in the treatment group reported spending less coli in water in treatment communities: E. coli contamina- money on illness-related expenditures in the previous two tion at the point of collection decreased from a prevalence months compared to what caregivers reported spending in of 64 percent in control taps down to 15 percent in treat- the control group – a difference that amounted to 40 Ban- ment taps. gladeshi taka (or $1.35 USD after adjusting for purchasing power parity) per child. Caregivers in the treatment group The positive impact on child health – the reduction were also slightly less likely to report that their child had in diarrheal disease – was larger in Dhaka than in consumed antibiotics in the past 2 months (with 40 percent Tongi, possibly because water quality in Dhaka was of parents reporting antibiotic use in treatment compared worse to begin with. to 44 percent in control). There were no significant dif- ferences between the groups in respiratory illness or other Children in the treatment group in Dhaka saw a 38 percent related illnesses, or measures of child growth (weight-for- reduction diarrhea compared to an 18 percent reduction age, height-for-age). The proper dosage of chlorine also appears to be The relative low-cost of the system suggests it may critical for ensuring community members accept be more scalable than other alternatives. the chlorinated water. The device was not on the market during the study pe- The chlorine doser was designed to minimize the taste of the riod, but Medentech’s estimated sale and refill price for a chlorine. In the piloting phase and in some sites during the single device were $20 and $25, respectively. Adding in main study, community members complained of the chlo- the cost of installation, maintenance, and communica- rine taste in the water. Researchers believe that accurate and tion, researchers estimate the cost of the full system to be automated chlorine dosing – that is, below the level where $US 3.62 per household a month, or $0.90 per person a people can detect the taste, but still at a level where it is effec- month. In comparison, the initial investment cost of provi- tive at disinfecting the water – will help ensure community sion of household water connections in Asia is estimated members accept and drink the water. to cost $204,000 per person. Point-of-use treatment could be much cheaper–an estimated $260 per person, but this WATER AND SANITATION kind of approach requires behavior change, which has been a challenge to sustain. Conclusion These results suggest that technologies that disinfect water to storage tanks, other automated chlorination technolo- at the point of collection can be developed to reduce disease gies for disinfecting water at the point of collection have in burgeoning slums in low-resource settings. Unlike home emerged that are low cost and compatible with other types water treatment, the approach evaluated here is likely effec- of water infrastructure, expanding the potential for scale up tive because it is “passive”–– the chlorine is automatically in low-income settings. added to the water so it doesn’t require any change of habits The difference in impact between the two study sites or behaviors of community members. suggests that the intervention might have the largest health Given its effectiveness and relatively low cost, this de- benefits in settings where users are accessing water points centralized approach to water treatment has the potential connected to large piped water networks supplying water to be implemented at scale and may represent a sound intermittently. Further research in other settings will be public investment. Although the Aquatabs Flo is currently needed to clarify where this intervention can have the most only compatible with water collection points connected health benefits. The Strategic Impact Evaluation Fund, part of the World Bank Group, supports and disseminates research evaluating the impact of development projects to help alleviate poverty. The goal is to collect and build empirical evidence that can help governments and development organizations design and implement the most appropriate and effective policies for better educational, health, and job opportunities for people in low and middle income countries. For more information about who we are and what we do, go to: http://www.worldbank.org/sief. The Evidence to Policy note series is produced by SIEF with generous support from the British government’s Department for International Development and the London-based Children’s Investment Fund Foundation (CIFF). 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