New York City drinking water supply and quality report 2023
In 2023, New York City’s water supply system delivered over one billion gallons of safe drinking water daily to 8.8 million NYC residents and one million people in surrounding counties. The water comes from 19 reservoirs and three controlled lakes in a 2,000-square-mile watershed. The Catskill/Delaware supply provided 95% of the water, and the Croton supply provided 5%.
The Catskill/Delaware supply is treated with chlorine and UV light, and additional chemicals to maintain quality. The Croton supply is filtered and treated similarly. DEP conducted extensive water quality monitoring, performing over 357,700 analyses on 31,600 samples from the distribution system and 231,800 analyses on 13,200 samples from the watershed. Robotic monitoring took more than 2.4 million measurements.