Overview: When you tap your faucet does clean, pure water flow? Can your city supply enough water for industry, firefighting, and street cleaning? U.S. public water-supply systems serve nearly 99 percent of the population, yet few users know how the system of aqueducts, pipes, and pumps work. Learn the colorful history of the water systems in Chicago, New York City, and Los Angeles when we scour the past and look to the future, including desalination plants that turn seawater into drinking water.