Evaluation
In Western Kenya, researchers compared three different approaches to subsidizing dilute chlorine solution to treat drinking water: a partial subsidy, a twelve month supply of free chlorine through monthly vouchers, and a twelve month supply of free chlorine hand-delivered. Safe water rates were much lower for households who had to co-pay for chlorine, but similar between households who received chlorine for free and households who had to redeem complimentary vouchers. This suggests that vouchers screened out households that would accept but not use the product under free immediate distribution, thereby keeping most of the benefits of free distribution while reducing wastage.