New York City water supply system

Early years of Collect Pond. Bayard's Mount, a hillock, is in the left foreground. Prior to being levelled around 1811 it was located near the current intersection of Mott and Grand Streets. New York City, which then extended to a stockade which ran approximately north–southeast from today's Chambers Street and Broadway, is visible beyond the southern shore. Until the eighteenth century, New York City solely depended on primitive means such as wells and rainwater reservoirs to collect water for daily use. The first public well was dug in Bowling Green in 1677, and the first reservoir was built on the East Side of Manhattan in 1776 after the population grew up to 22,000. Collect Pond, or "Fresh Water Pond", was a body of fresh water in what is now Chinatown in Lower Manhattan. For the first two centuries of European settlement in Manhattan, it was the main water supply system for the growing city. Later, the city was aware of its deteriorated water quality, owing to its rapid population growth (from 60,000 to 200,000 from 1800 to 1830), which had a considerable danger of causing epidemics. In April 1831, a new water supply and distribution system opened, for fighting fires. It included a well and cistern on 13th Street between Bowery (today 4th Avenue) and Third Avenue, which was then at the northern fringes of the city. The well was immense—16 feet across and 112 feet deep—blasted largely through rock, resulting in a quarry of over 175,000 gallons of water. A steam engine had the capacity to lift nearly half a million gallons a day. An octagonal iron tank, 43 feet in diameter and 20 feet high was installed atop a 27-foot-high stone tower. Mains under Broadway and the Bowery delivered the water to hydrants on Pearl, William, Hudson, and a dozen other major streets, in six-, ten-, and twelve-inch pipes, delivering water to a height of 60 feet above the highest streets. Old and New Croton Aqueducts The city's first aqueduct, the Croton Aqueduct, was built between 1837 and 1842 from the Croton River in Westchester County down to Manhattan, a distance of . The aqueduct was supported by the Old Croton Dam. The Old Croton Aqueduct's capacity was around 90 million gallons per day. To meet the city's growing needs, the city started construction of the New Croton Aqueduct in 1885. The New Croton Dam was added in 1906. The Old Croton Aqueduct continued supplying water to the city until 1955 and closed in 1965. Catskill Aqueduct In 1905, the city's newly established Board of Water Supply launched the Catskill Aqueduct project, which would play an additional role in supplying the city's ever-growing population of residents and visitors. Construction of the system began in 1907. Portions of the Catskill system began operation in 1916, and the overall system of dams, reservoirs and tunnels was complete by 1924. The Schoharie Reservoir was added to the system and began operation in 1926. The Catskill system has an operational capacity of approximately 850 million gallons per day. Within the city's overall water system, the Catskill Aqueduct is the furthest away from the city, approximately . Construction of the Delaware Aqueduct began in March 1937. The aqueduct was completed in 1944. From 1950 to 1964, Rondout, Neversink, Pepacton and Cannonsville reservoirs were established successively to complete the Delaware System. The Delaware Aqueduct supports half of the whole city's water usage by supplying more than 500 million gallons of water daily. == Responsible agencies ==

Responsibility for the city water supply is shared among three institutions: the New York City Department of Environmental Protection (DEP), which operates and maintains the system and is responsible for investment planning; the New York City Municipal Water Finance Authority (NYW), which raises debt financing in the market to underwrite the system's costs; and the Water Board, which sets rates and collects user payments. New York City Department of Environmental Protection The DEP has a workforce of over 7,000 employees. It includes three bureaus in charge of, respectively, the upstate water supply system, New York City's water and sewer operations, and wastewater treatment: • The Bureau of Water Supply manages, operates, and protects New York City's upstate water supply system to ensure the delivery of a sufficient quantity of high quality drinking water. The Bureau is also responsible for the overall management and implementation of the city's $1.5 billion Watershed Protection Program. • The Bureau of Water and Sewer Operations operates and maintains the water supply and sewerage system. It is also responsible for the operation of the Staten Island Bluebelt, a natural alternative to storm sewers, which occupies approximately of land in the South Richmond area of Staten Island. This project preserves streams, ponds and other wetland ("bluebelt") areas, allowing them to perform their natural function of conveying, storing and filtering storm water. • The Bureau of Wastewater Treatment operates 14 water pollution control plants treating an average of of wastewater a day; 95 wastewater pump stations; eight dewatering facilities; 490 sewer regulators; and of intercepting sewers. New York City Municipal Water Finance Authority The NYW finances the capital needs of the water and sewer system of the city through the issuance of bonds, commercial paper, and other debt instruments. It is a public-benefit corporation created in 1985 pursuant to the New York City Municipal Water Finance Authority Act. The authority is administered by a seven-member Board of Directors. Four of the members are ex officio members: the Commissioner of Environmental Protection of the City, the Director of Management and Budget of the City, the Commissioner of Finance of the City, and the Commissioner of Environmental Conservation of the State. The remaining three members are public appointments: two by the Mayor, and one by the Governor. New York City Water Board The New York City Water Board was established in 1905. It sets water and sewer rates for New York City sufficient to pay the costs of operating and financing the system, and collects user payments from customers for services provided by the water and wastewater utility systems of the City of New York. The five board members are appointed to two-year terms by the mayor. == Infrastructure ==

New York City's water system consists of aqueducts, distribution pipes, reservoirs, and water tunnels that channel drinking water to residents and visitors. A comprehensive raised-relief map of the system is on display at the Queens Museum of Art. Until the early 21st century, some places in southeastern Queens received their water from local wells of the former Jamaica Water Supply Company. Reservoirs and aqueducts The water system has a storage capacity of and provides over per day of drinking water to more than eight million city residents, and another one million users in four upstate counties bordering on the system. Three separate sub-systems, each consisting of aqueducts and reservoirs, bring water from Upstate New York to New York City: • The New Croton Aqueduct, completed in 1890, brings water from the New Croton Reservoir in Westchester and Putnam counties. • The Catskill Aqueduct, completed in 1916, is significantly larger than New Croton and brings water from two reservoirs in the eastern Catskill Mountains. The latter two aqueducts provide 90% of New York City's drinking water, and the watershed for these aqueducts extends a combined . Two-fifths of the watershed is owned by the New York City, state, or local governments, or by private conservancies. The rest of the watershed is private property that is closely monitored for pollutants; development upon this land is restricted. In 2025 the city announced the purchase of additional land near the Kensico Reservoir. The water is monitored by robotic buoys that measure temperature as well as pH, nutrient, and microbial levels in the reservoirs. A computer system then analyzes the measurements and makes predictions for the water quality. In 2015, the buoys took 1.9 million measurements of the water in the reservoirs. The compound is the largest ultraviolet germicidal irradiation plant in the world; it contains 56 UV reactors designed to treat up to per day. While all of the city's water goes through the disinfection process, only 10% of the water is filtered. The Croton Water Filtration Plant was built to address constant turbidity problems that are specific to the Croton water supply system. The plant was completed in 2015 at a cost of over $3 billion. The facility was constructed under Van Cortlandt Park in the Bronx and filters water delivered by the New Croton Aqueduct. The plant, which is bigger than Yankee Stadium, The city government agreed to rehabilitate the New Croton Aqueduct and build a filtration plant. The plant includes a UV disinfection system. The city had been studying possible sites for such a plant for more than 20 years in both the Bronx and Westchester. Tunnels and distribution system Tunnels From the Hillview reservoir water flows by gravity to three tunnels under New York City. Water rises again to the surface under natural pressure, through a number of shafts. • The partially-completed New York City Water Tunnel No. 3, the largest capital construction project in New York City's history (see Ongoing repairs and upgrades). It starts at Hillview Reservoir in Yonkers, New York then crosses under Central Park in Manhattan, to reach Fifth Avenue at 78th Street. From there it runs under the East River and Roosevelt Island into Astoria, Queens. From there it will continue on to Brooklyn. Distribution The distribution system is made up of an extensive grid of water mains stretching approximately . , it costs the city $140 million to maintain these mains. Scientists from the city measure the water every day, totaling over 1,300 stations per month, at up to 546 locations. The samples are then tested for microorganisms, toxic chemicals, and other contaminants. In 2015, the DEP performed 383,000 tests on 31,700 water samples. ==Ongoing repairs and upgrades==

Leaks were first discovered in the Delaware Aqueduct in 1988, with water losses up to per day. In 2010 the city announced a plan for a major repair project for the aqueduct. In 2013 work began on a bypass tunnel under the Hudson River, the largest construction project in DEP's history. The tunnel construction completed in 2019 and the overall bypass project is expected to be complete in 2027. In 2018, the city announced a US$1 billion investment to protect the integrity of its municipal water system and to maintain the purity of its unfiltered water supply. A significant portion of the investment will be used to prevent the turbidity that might be caused by climate change, including relocating the residents and cleaning up decaying plantations near the watersheds, and conducting flood-preventing research for infrastructures near the watersheds. According to Eric A. Goldstein, a senior lawyer for the Natural Resources Defense Council: "This is no time to let down one’s guard". ==See also==