In rural areas where piped-water infrastructure is too expensive or difficult to maintain, the burden of water collection falls primarily on women and young children. Though they may walk hours, the sources they have access to are often dangerously polluted. With so many people relying on the same sources to wash dishes and clothes and to give their livestock something to drink, preserving cleanliness is a demanding challenge. Fecal contamination from surface rainwater runoff makes matters worse.

Fortunately, a wide variety of relatively inexpensive water-improvement technologies are now at our disposal. Scientists have improved age-old tools like ceramic filters and…