Trickle Down: Diffusion of Chlorine for Drinking Water Treatment in Kenya

We study the distribution of dilute sodium hypochlorite to treat drinking water in homes in rural Kenya. Using a randomized evaluation, we find large impacts of receiving a six-month supply of free chlorine. At the time of follow-up, 58% of treatment households had detectable chlorine in home water on an unannounced visit and there was a 69% reduction in water contamination as measured by the fecal indicator bacteria E. coli. Child diarrhea rates fell by 35-40%. However, data from a subset of households given coupons for discounted chlorine in local shops indicate that demand for the product is very low at even a small cost. We do not find that households with young children, who stand to benefit most from cleaner water, have a higher valuation for it. Based on exogenous variation in the proportion of study households in a given community who were included in the treatment group, we find that the effect of social networks on adoption is moderate in comparison to the take-up impacts of getting free chlorine. In a follow-on study, we analyze social marketing messages, chlorine promoters, and installation of chlorine dispensers at water collection points as alternate means of encouraging adoption. Consistent with our earlier results, price seems to be a major impediment to use. Of the methods we evaluate, chlorine dispensers offer by far the greatest promise for sustainable adoption at scale by drastically reducing the cost of supplying communities with free chlorine and harnessing social network effects.