Ancient hunters and gatherers remained near water supplies when they could, devising means to carry water with them when necessary and tapping water sources below the surface or from plants. The Tigris and Euphrates, Nile, and Indus rivers supplied ample water for the ancient civilizations near them, and wells dating back to 3000 B.C. are the earliest manmade water sources and served small communities. Caves functioned as early storage chambers--cisterns--for water diverted for later use, as did crevices and fissures in rocky surfaces. Prized for its purity, rainwater often was caught in rooftop containers in the Middle East and the Mediterranean, and as construction methods became more sophisticated, cisterns were built underground. Istanbul's Hall of a Thousand and One Columns, built in the sixth century B.C., is one of the largest such cisterns.

The modern-day equivalent of the cistern...