New York City is entering the final phase of its most ambitious water infrastructure project in history: the Delaware Aqueduct repair project, a $2-billion initiative decades in the making.
This critical effort, launched by Mayor Eric Adams and New York City Department of Environmental Protection (DEP) Commissioner Rohit Aggarwala, aims to fix a large leak in the world’s longest continuous tunnel—the Delaware Aqueduct, which provides about 600 million gallons of drinking water daily to nearly 10 million residents.
No small task.
The Problem: A 35-Million-Gallon Leak. The Solution...
For over two decades, the city has grappled with leaks that siphon 35 million gallons of water each day from the aqueduct, primarily near Newburgh, N.Y., 66 miles north of New York City.
In response, the city has been constructing a 2.5-mile-long bypass tunnel that runs 600 feet beneath the Hudson River to reroute water around the damaged portion of the aqueduct. The final phase of the project, currently under way, will connect the bypass tunnel to the main aqueduct and permanently seal the leaking sections near Newburgh and Ulster County.
“New York City’s tap water is the envy of the world—it’s why we have the best pizza and bagels in the country,” Adams said during the project launch. He highlighted the importance of ensuring a reliable water supply, noting that this project is essential for New Yorkers to continue enjoying the billion gallons of drinking water they consume every day.
The Delaware Aqueduct, which began operation in 1944, is a feat of engineering, running 85 miles from four Catskill Mountain reservoirs to the city. Since the 1990s, the aqueduct has been losing millions of gallons of water per day, making this repair project urgent for both the city's infrastructure and its residents.
Diagram showing the existing aqueduct and the bypass tunnel beneath the Hudson River.NYC Water
Maintaining Water Quality
Throughout the repairs, New Yorkers may notice subtle changes in their water’s taste or aroma as DEP temporarily increases its reliance on the Croton Watershed, a network of reservoirs in Westchester and Putnam counties.
However, city officials have reassured residents that the water remains clean, safe, and of high quality.
“Just like different brands of bottled water taste a bit different, so do our different reservoirs,” Aggarwala said. “While some residents may notice a temporary, subtle difference in taste or aroma during the repairs, our water remains clean and safe to drink.”
To help maintain water quality during the repairs, the Croton Filtration Plant has been modified with advanced filtration systems, including granular activated carbon, similar to those used in household water filters.
Engineering Marvels and Long-Term Planning
The Delaware Aqueduct is an engineering marvel, originally designed to use gravity alone to deliver water from the Catskill Mountains to New York City. Over the past 11 years, engineers have constructed the bypass tunnel, and now they are connecting it to the existing aqueduct to prevent further leaks.
“This heroic project, which took over 20 years to prepare for, shows the incredible ingenuity of New York's civic employees who give their all every day to keep this city running,” said Deputy Mayor for Operations Meera Joshi.
Former DEP Commissioner Vincent Sapienza praised the project’s foresight, saying, “Our water supply system is an engineering feat that made the city what it is today.” He emphasized the significance of such efforts to maintain the infrastructure that has been the backbone of New York’s growth and development.
