New York City"s water system is, by every measure, an engineering marvel. Delivering 1.2 billion gallons of water each day to more than nine million people, it is a complex network of reservoirs stretched out over a vast upstate region and connected by a web of subterranean aqueducts to rival the aqueducts of the ancient Romans. The system, so pivitol to the development of the nation"s largest city and its northern suburbs, was realized over the past century and a half, and indeed is still being built beneath New York City"s subways and skyscrapers. This is the first comprehensive history of that system from colonial times to the present.