Willingness to pay for a sanitation-adjusted person year: evidence from Malawi

There are 48 countries where >5 million people lack a basic toilet. This makes sanitation resource allocation a live issue in infectious disease policy, but toilet user preferences often give greater weight to quality of life gains such as privacy and safety. These quality-of-life gains are never valued in benefit-cost analyses, risking resource misallocation. This study estimates the monetary value of a sanitation-adjusted person year, analogous to the quality-adjusted life year. We conducted a contingent valuation willingness to pay (WTP) study with 300 participants in rural Malawi. Participants first answered questions for the sanitation-related quality of life index (SanQoL-5), scored 01. They were then offered a hypothetical toilet upgrade and asked about WTP for resulting SanQoL-5 gains, first via double-bound dichotomous choice and then maximum WTP. The average WTP for a sanitation-adjusted person year was US$ 6.2 (95% CI: 3.0-9.3), based on regression adjusted for WTP for a benchmark good (maize). Experiencing a gain in SanQoL-5 from 0.45 to 0.75 on the 0-1 scale would therefore be worth about $2/year, a consequential benefit to the 700 million people living on less than $2.15 per day. Our findings enable the valuation of quality of life in sanitation benefit-cost analysis.