Diaries to Increase the Adoption of Chlorine Tablets for Water Purification by Poor Households

Over half-a-million children die annually from diarrheal disease. Despite the availability and known benefits of chlorine tablets, vulnerable populations in developing countries rarely use chlorine to decontaminate their drinking water even when offered for free. We test the hypothesis that the low uptake by poor households is an information problem. The episodic nature of diarrhea makes it difficult to detect that chlorine tablets have any effect on diarrhea, so households quickly abandon using chlorine tablets after trying them. We conduct an experiment where we offer a control group and a treatment group standard information about local diarrhea incidence and the effectiveness of chlorine tablets, along with chorine tablets for free. The treatment group, however, is also given training with a diary that helps them track their children’s cases of diarrhea. The diary is used for three months before and three months after the chlorine tablets are offered. The diary allows households to learn about their household incidence of diarrhea without chlorine and then see how it changes once they start using chlorine. We then compare the rate chlorine tablets are accepted in the treatment group with a control group. Using intent-to-treat regression specifications, with and without controls for household characteristics, reveals that the treatment group consistently had much higher chlorine adoption rates than the control group. The overall presence of chlorine in household water 18 months after chlorine was first offered was 86% in the treatment group but only 29% in the control group. Consistent with this finding, the children in the treatment group were significantly taller and weighed more than the control group children. Our study suggests that the medical diary can be an effective way to convince poor households of the effectiveness of chlorine tablets and therefore dramatically increase adoption rates. Widespread use of the diary is a cost-effective way to increase global chlorine adoption and help lower diarrhea deaths and illnesses of children worldwide. Moreover, medical diaries like ours may also increase adoption rates of other cost-effective health measures that suffer from low adoption rates.