Nature Water, Published online: 02 June 2026; doi:10.1038/s44221-026-00647-4 Safe drinking water is vital for reducing childhood diarrhoea, but evidence on which service elements matter most has been unclear. Data from 24 low- and middle-income countries show that safely managed drinking water reduces child diarrhoea risk, with water availability and absence of faecal contamination at point of use providing the strongest protection.