World Rivers Day falls on the fourth Sunday of September each year, and in 2026 that date was 27 September. The observance is meant to encourage the conservation of rivers and the protection of freshwater ecosystems that depend on them. It also seeks to make people more aware of why rivers matter, for drinking water, farming, biodiversity and livelihoods. Because the day is fixed by the calendar rather than a set date, it moves each year, and in 2026 it was marked on the last Sunday of the month, 27 September.