New York City’s century-old main water pipe is closed for repairs. The water supply will not be affected, but the taste of the water may change.

On September 30, Mayor Adams took a trip to the Queens Museum to discuss the Delaware Aqueduct and its upcoming repairs. Starting this week, New York City’s main water supply pipeline will undergo emergency repairs, expected to last for eight months. During this time, the city will rely on alternative water sources, and while officials believe that residents’ tap water will remain largely unaffected, they do anticipate a slight decline in water quality and some changes in taste.

The Delaware Aqueduct, nearly a century old and stretching 85 miles, holds the distinction of being the longest municipal water supply pipeline in the world. It runs through the Catskill region’s watershed in upstate New York and the Hudson River valley, delivering clean water from the Delaware River basin to New York City, where freshwater resources are increasingly limited.

Since the 1990s, the northern section of the aqueduct has faced multiple leaks, with current losses reaching an alarming 35 million gallons of water daily. To tackle this issue, a new bypass pipeline has been constructed to divert water away from the leaking sections. The aim of the current closure is to connect the existing pipeline to this new segment, with the overall project projected to cost around $2 billion.

During the repairs, four upstream reservoirs will be unable to supply water to New York City, while downstream reservoirs will continue to operate as usual, resulting in an expected reduction of the total water supply by half. Paul Rush, Deputy Commissioner of the Department of Environmental Protection (DEP), noted that the repairs were strategically scheduled for the fall and winter, when water usage typically decreases. The supply gap will be filled by the Croton River basin, which includes over a dozen reservoirs and three natural lakes. However, officials caution that the water quality from the Croton River basin is generally lower than that of the Delaware River, containing higher levels of minerals and algae that need filtering before entering the city’s water system.

Data shows that the Croton filtration plant, located in the Bronx, will only meet about a quarter of the city’s water demand during construction. The rest will be compensated through a blending process, mixing Croton water with high-quality water from the Catskill region in carefully calibrated ratios to dilute the contaminants. Experts have raised concerns about whether the partially filtered Croton River water can meet safe drinking standards.

City officials have reassured residents that all tap water will comply with regulatory standards. Rush emphasized that every drop of water entering the supply system undergoes rigorous testing and is treated with chlorine and ultraviolet light to eliminate pathogens and other pollutants. Rohit Aggarwala, the Commissioner of the Department of Environmental Protection, also addressed concerns in a press release, stating that while the taste of the water might change slightly during this period, it does not reflect a decline in water quality.