New York City tap water is widely considered safe to drink and consistently meets or exceeds all federal and state water quality standards. The city’s water supply is often lauded for its high quality compared to other major metropolitan areas across the United States. This reputation stems from a comprehensive system that protects water at its source and applies rigorous treatment and testing protocols before it ever reaches the city limits.
The Source of NYC’s Water Supply
The purity of New York City’s water begins over 100 miles upstate in a vast, protected watershed system covering nearly 2,000 square miles. This system is split into the Catskill/Delaware and Croton watersheds, which collectively supply over one billion gallons of water daily to nine million people. The Catskill/Delaware system, located west of the Hudson River, provides about 90% of the city’s water needs.
The protected nature of this land contributes to the naturally high quality of the source water. The water travels through a network of 19 reservoirs and three controlled lakes, with 97% of the water flowing to the city by gravity alone, minimizing the need for extensive pumping. Because of the pristine condition of the Catskill/Delaware source, New York City is one of the few large municipalities in the United States permitted to deliver a majority of its water without conventional filtration. The Croton system, the older and smaller source, supplies the remaining water and is filtered to supplement the main supply.
Treatment Processes and Regulatory Oversight
Despite the high quality of the source, the water undergoes treatment to ensure it remains safe and clean for consumption. The New York City Department of Environmental Protection (DEP) is the agency responsible for maintaining this oversight and quality. The treatment regimen involves several disinfection steps mandated by health regulations, including the federal Safe Drinking Water Act.
The two primary disinfection methods are chlorination and ultraviolet (UV) light treatment, which are highly effective at neutralizing microbial contaminants. The DEP also adds a food-grade additive, orthophosphate, to the water supply. This compound forms a protective film on the inside of pipes, preventing lead and other metals from dissolving into the water as it travels through the distribution system.
Testing is a constant process, with scientists collecting samples hundreds of times each day from the reservoirs, aqueducts, and a network of 1,000 street-side sampling stations across the five boroughs. This extensive monitoring checks for a range of contaminants, including heavy metals, chemicals, and microbial threats. The city’s ability to maintain its filtration avoidance status is dependent on consistently meeting these stringent water quality criteria.
Addressing In-Home Water Quality Concerns
The water leaving the municipal distribution system is virtually lead-free, but contamination concerns can arise once it enters the plumbing of individual buildings. The primary risk for elevated lead levels comes from aging service lines and interior plumbing fixtures in older construction, particularly buildings built before 1989. These older components may contain lead solder, brass fixtures, or even lead service lines, which are the pipes connecting the city water main to the building.
The orthophosphate treatment helps reduce lead leaching, but residents should still take proactive steps to minimize potential exposure. A simple and effective practice is to flush the cold water tap for at least 30 seconds, or until the water runs noticeably colder, before using it for drinking or cooking. This action clears any standing water that may have absorbed lead from the interior plumbing.
It is also important to never use hot water from the tap for consumption, as lead dissolves more easily in warmer water. Residents with concerns about their specific building’s plumbing can request a free lead testing kit from the DEP. While the water is safe, a point-of-use filter certified to remove lead can offer an additional layer of protection, especially in older homes, or simply improve the taste by removing chlorine.