Leading Scientists say New York City on Track to Continue Unfiltered High Quality Drinking Water Into the Future

April 23, 2026

DEP Anticipates Continued Success of Programs Protecting New York City's World-Renowned Drinking Water in Move to Renew Filtration Waiver

NEW YORK-The NYC Department of Environmental Protection (DEP) announced today that a group of top independent scientists has reviewed the City's drinking water protection programs and found them to be strong, effective, and in the public's best interest. Their findings support the City's long standing approach of keeping its Catskill and Delaware water supplies clean at the source-so the water doesn't need to be filtered before it reaches New Yorkers' taps.

At the same time, both the scientific panel and a new DEP white paper point out that climate change and evolving regulations are creating new challenges. These changes mean the City must stay vigilant and continue planning ahead to protect water quality for the long term.

The findings are published in The Future of Filtration Avoidance, a new DEP white paper developed with input from the Scientific Advisory Panel, state regulators, and watershed partners. The report comes as DEP begins formal discussions with the New York State Department of Health to renew the City's filtration waiver-known as the Filtration Avoidance Determination, or FAD-for another 10 years.

"New York City's water system is one of the best examples in the world of protecting drinking water right at its source," said DEP Commissioner Lisa F. Garcia. "This report shows that our approach continues to keep New Yorkers safe, and it also gives us a clear roadmap for how we can stay ahead of new challenges. By planning smartly and working closely with our watershed partners, we can continue delivering the high-quality water New Yorkers expect well into the future."

For more than 30 years, New York City has been allowed to avoid building a massive filtration plant for its water sourced from the Catskill Mountains region because it meets some of the strictest water protection and treatment standards in the world. Instead of filtering the water, the City protects it at the source-through land acquisitions and management, farming partnerships, forest restoration, and other science-based programs bolstered by extensive water quality testing and effective treatment. These efforts have saved New Yorkers billions of dollars. Without the waiver, the City would need to build what would likely be the most expensive capital project in its history, plus pay for ongoing operating costs. Protecting the water at its source is not only environmentally smart-it helps keep water bills affordable.

An independent panel of 11 experts from across the country spent the past year reviewing DEP's research and the biggest risks to keeping the water unfiltered. They concluded that DEP's understanding of these risks is "scientifically sound" and that continuing to avoid filtration remains the best long-term strategy.

"Our independent review concludes that filtration avoidance remains a viable and responsible strategy for New York City," said Dr. Paul Westerhoff, Chair of the independent Scientific Advisory Panel and Director of the Arizona State University Global Center for Water Technology. "DEP is focused on the right risks and is applying rigorous science to manage them. With continued proactive planning and investment, the City is well positioned to sustain this approach while protecting public health."

The panel also agreed that the biggest challenges ahead include:

• Climate change: More intense storms, droughts, and rapid weather swings can wash more sediment and organic material into reservoirs. DEP is expanding climate modeling and updating operations to stay ahead of these changes.
• Disinfection byproducts (DBPs): These form when chlorine interacts with natural organic matter. They are currently the tightest area of regulatory compliance. DEP is improving monitoring, testing new treatment options, and refining operations to stay within limits.
• Emerging contaminants: Substances like PFAS and microplastics are being studied nationwide. The panel found no current threat to NYC's water, but DEP will continue leading research and monitoring as science and regulations evolve.

The report makes clear that DEP's programs must continue to evolve. Some long standing programs have achieved their goals and now require maintenance rather than expansion. Others may need to be updated or redesigned to address new risks.

This moment marks a shift: DEP and its watershed partners must reassess and adapt their strategies to ensure the City can continue avoiding filtration while protecting public health for decades to come.

About the NYC Department of Environmental Protection

DEP manages New York City's water supply, providing approximately 1 billion gallons of high-quality drinking water each day to nearly 10 million residents, including 8.3 million in New York City. The water is delivered from a watershed that extends more than 125 miles from the city, comprising 19 reservoirs and three controlled lakes. Approximately 7,000 miles of water mains, tunnels and aqueducts bring water to homes and businesses throughout the five boroughs, and 7,500 miles of sewer lines and 96 pump stations take wastewater to 14 in-city treatment plants. DEP also protects the health and safety of New Yorkers by enforcing the Air and Noise Codes and asbestos rules. For more information, visit nyc.gov/dep, like us on Facebook, or follow us on X.