Updated November 1, 2026

New York City tap water: mountain reservoirs, no filter, and the real lead question

More than 8 million city residents drink water collected as far as 125 miles north, in the Catskills and the Hudson Valley. It arrives soft and lightly treated. The thing worth checking isn't the reservoir; it's the pipe between the street and your faucet.

A watershed the size of Delaware

New York's supply comes from 19 reservoirs and three controlled lakes spread over a watershed of nearly 2,000 square miles, according to the city's 2025 water quality report. There are three systems. In 2025 the Catskill and Delaware systems together delivered 91.3% of the water and the older Croton system delivered 8.7%. The city also holds a permit for a groundwater system in southeast Queens, but it isn't a routine part of the supply.

Most of the water travels by gravity through the 92-mile Catskill Aqueduct and the 85-mile Delaware Aqueduct. The Delaware Aqueduct runs deep underground and is, as DEP notes, the longest tunnel in the world. The final stop before the five boroughs is Hillview Reservoir in Yonkers, where a $1.2 billion modernization is under way under a federal consent judgment.

Why most of it is never filtered

New York is one of only five large U.S. cities that doesn't filter its surface water. The Catskill/Delaware supply operates under a Filtration Avoidance Determination, a waiver that holds only as long as the watershed stays clean. DEP says it spends more than $100 million a year on that protection: buying land, upgrading upstate sewage plants and working with farms. The current waiver runs through at least 2027.

Instead of filters, the water gets chlorine, then ultraviolet light at the Catskill/Delaware UV facility, which the report says can treat more than two billion gallons a day. Before it enters city mains, DEP adds food-grade phosphoric acid (to coat pipes), sodium hydroxide (to raise pH and cut corrosion) and fluoride. Croton water takes a different route: coagulation, dissolved air flotation and filtration at an underground plant in the Bronx, then the same chlorine, UV and corrosion treatment.

Soft water, so skip the softener pitch

DEP's 2025 table lists hardness across 313 distribution samples at an average of 32 mg/L, with a range of 18 to 100 mg/L. In grains per gallon that's about 2 on average, and the report itself labels anything up to 3 gpg as soft. If a salesperson recommends a whole-home softener for a Manhattan or Queens apartment, the city's own numbers don't support it. You can confirm with our hardness converter.

Lead: the buildings, not the mains

DEP states there is no lead in its roughly 7,000 miles of aqueducts, tunnels and mains. Lead enters at the building: homes built before 1961 may have lead service lines, and older fixtures can add more. That shows up in the tap sampling. In the 2025 report the 90th-percentile lead result at sampled homes was 10 µg/L, under the 15 µg/L action level, but 16 of 326 homes tested above 15, with a highest reading of 155 µg/L. EPA's compliance data for the system shows the same 10 µg/L figure.

Practical steps from the report: run the cold tap for a while when water has sat in the pipes for hours, use only cold water for cooking and baby formula, and clean faucet aerators monthly. If your building is pre-1961, a pitcher or faucet filter certified to NSF/ANSI Standard 53 for lead is a cheap safeguard. Our filter selector shows what certification to look for.

PFAS and the odd one-off result

In EPA's nationwide UCMR 5 sampling, no PFAS were reported for the NYC system. DEP's own annual sampling did catch PFOA and PFHxA once each, on January 8, 2025, at a single Bronx site in Van Cortlandt Village; neither showed up in the quarterly federal tests. The report also flags a cyanide hit and a toluene hit that it attributes to contaminated sample bottles. That level of footnoting is unusual, and it's worth reading the full report if you like detail.