Reducing the user burden in WASH interventions for low-income countries
Authors: Jean H Humphrey
Journal: The Lancet Global Health (2019)

Faecal-pathogen-free living environments, food, and drinking water are irrefutably fundamental to human health. Nonetheless, several controlled experiments have failed to prove that WASH interventions, designed to reduce faecal exposure, improve health outcomes.1Clasen T Boisson S Routray P et al.Effectiveness of a rural sanitation programme on diarrhoea, soil-transmitted helminth infection, and child malnutrition in Odisha, India: a cluster-randomised trial.Lancet Glob Health. 2014; 2: e645-e653Summary Full Text Full Text PDF PubMed Scopus (296) Google Scholar, 2Boisson S Stevenson M Shapiro L et al.Effect of household-based drinking water chlorination on diarrhoea among children under five in Orissa, India: a double-blind randomised placebo-controlled trial.PLoS Med. 2013; 10e1001497Crossref PubMed Scopus (59) Google Scholar, 3Null C Stewart CP Pickering AJ et al.Effects of water quality, sanitation, handwashing, and nutritional interventions on diarrhoea and child growth in rural Kenya: a cluster-randomised controlled trial.Lancet Glob Health. 2018; 6: e316-e329Summary Full Text Full Text PDF PubMed Scopus (242) Google Scholar, 4Humphrey Jean H Mbuya Mduduzi N.N Ntozini Robert et al.Independent and combined effects of improved water, sanitation, and hygiene, and improved complementary feeding, on child stunting and anaemia in rural Zimbabwe: a cluster-randomised trial.Lancet Glob Health. 2019; 7: e132-e147Summary Full Text Full Text PDF PubMed Scopus (153) Google Scholar These disappointing findings do not challenge the biological plausibility that water, sanitation, and hygiene (WASH) services are essential to health, but do suggest that low-cost WASH interventions—those often available to rural dwellers in low-income countries—might not reduce the extremely high concentrations of contamination characteristic of impoverished living conditions to the very low concentrations of contamination required for health.5Pickering AJ Null C Winch PJ et al.The WASH Benefits and SHINE trials: interpretation of WASH intervention effects on linear growth and diarrhoea.Lancet Glob Health. 2019; 7: e1139-e1146Summary Full Text Full Text PDF PubMed Scopus (85) Google Scholar One reason for the poor efficacy of low-cost WASH interventions is their requirement for high user adherence to consistent sustained behaviour change. For rural people in low-income countries, environmental hygiene requires not only widespread access to and use of improved sanitation, but also management of faeces from cohabitating domestic animals which makes up 67% of the household-level faecal mass;6Berendes DM Yang PJ Lai A Hu D Brown J Estimation of global recoverable human and animal faecal biomass.Nature Sustainability. 2018; 1: 679-685Crossref Scopus (29) Google Scholar hand hygiene requires prioritisation of scarce resources to purchase soap, spending hours each day collecting large volumes of water, and then prioritising these resources for handwashing; and clean drinking water might require households to purchase and mix chlorination solutions with measured volumes of water in designated clean covered containers, and be willing to drink water they find unpalatable. Thus, low-cost WASH interventions often fail to improve health because they require much more user effort, time, and compromise than is required from residents of high-income countries for WASH services. It is widely acknowledged that achieving high frequencies of adherence to these interventions is challenging.7Curtis VA Danquah LO Aunger RV Planned, motivated and habitual hygiene behaviour: an eleven country review.Health Educ Res. 2009; 24: 655-673Crossref PubMed Scopus (258) Google Scholar, 8Luoto J Najnin N Mahmud M et al.What point-of-use water treatment products do consumers use? Evidence from a randomized controlled trial among the urban poor in Bangladesh.PLoS One. 2011; 6e26132Crossref PubMed Scopus (49) Google Scholar All published evidence that handwashing promotion and point-of-use water chlorination interventions reduce diarrhoea comes from efficacy trials which implemented daily to fortnightly contact between promoters and participants; moreover, in a few instances where study populations were followed after efficacy trials ended, adherence often steeply declined and the effect on child diarrhoea disappeared once the intense intervention stopped.5Pickering AJ Null C Winch PJ et al.The WASH Benefits and SHINE trials: interpretation of WASH intervention effects on linear growth and diarrhoea.Lancet Glob Health. 2019; 7: e1139-e1146Summary Full Text Full Text PDF PubMed Scopus (85) Google Scholar Since this degree of intervention intensity is not feasible for programmes, it is improbable that these interventions will reduce diarrhoeal disease unless either alternative means of achieving high adherence are identified or the requirement for user behaviour change is reduced. In The Lancet Global Health, Amy Pickering and colleagues report results of a randomised trial done in two neighbourhoods of urban Bangladesh which directly addresses this challenge. They tested the effect of a device (Aquatabs Flo, Medentech, Inc., Wexford Ireland), which automatically chlorinates piped water, on child diarrhoea.9Pickering AJ Crider Y Sultana S et al.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.Lancet Glob Health. 2019; 7: e1247-e1256Summary Full Text Full Text PDF PubMed Scopus (19) Google Scholar As is common in low-income settings, the municipal piped water in the study area was delivered only intermittently; this limitation causes sporadic pressure drops in the piped networks which hydraulically facilitates entry of microorganisms into the pipe lumen through backflow or cracks.10Kumpel E Nelson KL Comparing microbial water quality in an intermittent and continuous piped water supply.Water Res. 2013; 47: 5176-5188Crossref PubMed Scopus (109) Google Scholar The device was fitted at the inlet of large water storage tanks fed by municipal piped water; the device did not require electricity and produced water with a sufficient chlorine residual to continue disinfecting water after collection if it was re-contaminated by dirty storage containers, utensils, or hands. Finally, in addition to testing the technology itself, the authors did preliminary work to identify a trade-off chlorine concentration that jointly optimised palatability and disinfection. This compromise dose resulted in a mean 0·14 ppm chlorine residual at point of use and left 15% of intervention household water samples with detectable Escherichia coli. Blinding was largely successful: participants could not accurately guess which intervention they had received and their best guess did not bias diarrhoea reporting. Trial results showed that this intervention, which delivered less-than-perfect disinfection but required no user effort (or even awareness of its presence) significantly reduced child diarrhoea by 23%. The intervention will not work for everyone in all situations for several reasons. First, the device is compatible with only a specific type of water system: in the study area this was one third of the water taps. Second, although 1·3 billion people have gained access to piped water since 2000, 2·9 billion (38%) of the global population still do not have any kind of access to piped water.11UNICEF–WHOProgress on household drinking water, sanitation and hygiene 2000–2017. Special focus on inequalities. United Nations Children's Fund–World Health Organisation, New York2019Google Scholar Third, the intervention effect size was six times greater in one of the study neighbourhoods compared with the other, suggesting it will not be clinically or cost effective in all contexts. Fourth, the chlorine dispensers had to be uninstalled in nine of 50 (18%) sites because communities complained of the smell and taste of chlorinated water: some people refused to drink water that was chlorinated at a concentration which most people could not detect. There is certainly no one-size-fits-all strategy for providing access to clean water throughout the world. However, the intervention reported in this paper is both specifically and conceptually an important step forward: this study shows that by removing the requirement of user behaviour change and slightly compromising effectiveness to achieve high uptake, a simple technology can have substantial public health benefit. I declare no competing interests. Effect of in-line drinking water chlorination at the point of collection on child diarrhoea in urban Bangladesh: a double-blind, cluster-randomised controlled trialPassive chlorination at the point of collection could be an effective and scalable strategy in low-income urban settings for reducing child diarrhoea and for achieving global progress towards Sustainable Development Goal 6.1 to attain universal access to safe and affordable drinking water. Targeting a low chlorine residual (<0·5 ppm) in treated water can increase taste acceptability of chlorinated drinking water while still reducing the risk of diarrhoea. Full-Text PDF Open Access