Today, more than 1 billion people lack access to safe drinking water. Within the next 25 years, fully one-third of the world’s population will experience severe water scarcity. It is clear that disparities in the availability and supply of fresh water are truly a matter of life and death, and constitute one of the great governance imperatives of our time. This publication summarizes the results of three decades of IDRC-supported research on water supply. It demonstrates that some of the most powerful responses to water scarcities have been mounted at the community or local level — in households, farmers’ fields, villages, and city neighborhoods.