Water is Life, Clean Water Means Health

This study examines the impact of water purification on long-run old-age mortality. We examine the effects of early-life and childhood exposure to improvements in water quality due to citywide water filtration programs in 25 major American cities on later-life old-age longevity of male individuals. We employ data from Social Security Administration death records linked with the 1940 census. The difference-in-difference regressions suggest an improvement in male longevity of about 3.2 months. A series of balancing tests do not reveal evidence that changes in sociodemographic and socioeconomic characteristics of individuals confound the estimates. We also implement a full battery of sensitivity analyses and show that the effect is robust across specifications, subsamples, and functional form checks. Analyses using 1950–70 censuses suggest that a portion of the long-term links can be explained by improvements in individuals’ education and income as a result of early-life exposure to water filtration. We also show that treated cohorts reveal improvements in height and cognitive scores during early adulthood.