Croton Aqueduct

The honest starting point. New York lost 3,500 people to cholera in 1832, when its water came from wells, ponds and springs inside the city. The aqueduct's answer was a 41-mile channel carrying Croton River water, largely by gravity, which arrived on July 4, 1842. Clean water reached the city, but not every home. Cholera came back with greater force in the Sixth Ward in 1849, and a study of ward records found cholera deaths tracked where Croton pipes did and did not reach. That is the lesson every later entry absorbs: a pure source protects only the people it is piped to.