Publications by Author: Zwane, Alex Peterson

Each year, 1.6 million children die from diarrheal diseases; unsafe drinking water is a major cause. This paper reviews evidence from randomized trials on domestic water access and quality in developing countries, interpreting the results through a public economics framework. It argues that subsidies for water treatment are likely warranted, while more evidence is needed to assess the case for subsidizing programs to improve access to water. Multiple randomized trials show that water treatment can cost-effectively reduce reported diarrhea. However, many consumers have low willingness to pay for cleaner water, with less than 10% of households purchasing household water treatment under existing retail models. Provision of information on water quality can increase demand, but only modestly. Free point of collection water treatment systems designed to make water treatment convenient, salient, and public, combined with a local promoter, can generate take up of more than 60 percent. The projected cost is as low as \$20 per year of life saved, comparable to vaccines. In contrast, the limited existing evidence suggests many consumers are willing to pay for better access to water, but it does not yet demonstrate that this improves health. Randomized impact evaluations have also generated a number of methodological insights, suggesting that: at least in some contexts, merely surveying households can lead them to change their behavior; separately randomizing offer and transaction prices does not yield evidence of sunk cost effects; revealed preference measures of clean water valuation are much lower than contingent valuation estimates; and randomized evaluations can be used to estimate parameters for structural policy simulations.

Using a randomized evaluation in Kenya, we measure health impacts of spring protection, an investment that improves source water quality. We also estimate households’ valuation of spring protection, and simulate the welfare impacts of alternatives to the current system of common property rights in water, which limits incentives for private investment. Spring infrastructure investments reduce fecal contamination by 66%, but household water quality improves less, due to recontamination. Child diarrhea falls by one quarter. Travel-cost based revealed preference estimates of households’ valuations are much smaller than both stated preference valuations and health planners’ valuations, and are consistent with models in which the demand for health is highly income elastic. We estimate that private property norms would generate little additional investment while imposing large static costs due to above marginal-cost pricing, private property would function better at higher income levels or under water scarcity, and alternative institutions could yield Pareto improvements.