The Croton Aqueduct or Old Croton Aqueduct was a large and complex water distribution system constructed for New York City

New York City

New York is the most populous city in the United States and the center of the New York Metropolitan Area, one of the most populous metropolitan areas in the world. New York exerts a significant impact upon global commerce, finance, media, art, fashion, research, technology, education, and...

 between 1837 and 1842. It brought water by the force of gravity alone 41 miles (66 km) from the Croton River

Croton River

The Croton River is a river in southern New York that begins where the East and West Branches of the Croton River meet a little way downstream from the Croton Falls Reservoir...

 in Westchester County into reservoirs in Manhattan

Manhattan

Manhattan is the oldest and the most densely populated of the five boroughs of New York City. Located primarily on the island of Manhattan at the mouth of the Hudson River, the boundaries of the borough are identical to those of New York County, an original county of the state of New York...

, where local water resources had become polluted and inadequate for the growing population of the city.
The island of Manhattan

Manhattan

Manhattan is the oldest and the most densely populated of the five boroughs of New York City. Located primarily on the island of Manhattan at the mouth of the Hudson River, the boundaries of the borough are identical to those of New York County, an original county of the state of New York...

, surrounded by brackish

Brackish water

Brackish water is water that has more salinity than fresh water, but not as much as seawater. It may result from mixing of seawater with fresh water, as in estuaries, or it may occur in brackish fossil aquifers. The word comes from the Middle Dutch root "brak," meaning "salty"...

 rivers, had a limited supply of fresh water available, which dwindled as the city grew rapidly after the American Revolutionary War

American Revolutionary War

The American Revolutionary War , the American War of Independence, or simply the Revolutionary War, began as a war between the Kingdom of Great Britain and thirteen British colonies in North America, and ended in a global war between several European great powers.The war was the result of the...

, and fresh water sources became polluted by effluent

Effluent

Effluent is an outflowing of water or gas from a natural body of water, or from a human-made structure.Effluent is defined by the United States Environmental Protection Agency as “wastewater - treated or untreated - that flows out of a treatment plant, sewer, or industrial outfall. Generally refers...

.