New York City’s tap water, often a point of pride for locals, may start tasting slightly different for a while, the NY Times reports.

Starting this week, the supply from a key watershed in the Catskills, which normally provides around 90 percent of the city’s drinking water, will be reduced by roughly half. To compensate, another, less commonly used source will step in to fill the gap.

A portion of the Delaware Aqueduct is being taken offline for essential maintenance, which will last for eight months. This means the city will lose access to a large portion of the Delaware section of the Catskill-Delaware watershed, a vital water source spanning five counties in upstate New York. This watershed is the largest unfiltered water supply in the country.

However, there’s a backup plan: A different watershed, which usually supplies around 10 percent of New York City’s water, will be called upon to pick up some of the slack. While this alternative source is safe, officials have noted that residents may notice a subtle change in the flavor of their tap water during this time as the city addresses necessary infrastructure upgrades.

“Just like different brands of bottled water taste a bit different, so do our different reservoirs,” explained Rohit T. Aggarwala, the commissioner of the Department of Environmental Protection, in a statement about the situation.

The Delaware Aqueduct, nearly 100 years old, stretches 85 miles from the Catskills down to the main reservoir in Yonkers, just outside New York City.

Back in the 1990s, engineers discovered leaks in a 2.5-mile stretch of the aqueduct near Newburgh, about 70 miles from the city, as well as at another spot further north. The leaks have been allowing up to 35 million gallons of water to escape each day.

The current closure of the aqueduct is intended to bypass the damaged section by connecting it to a new tunnel, which was completed three years ago. This marks the final stage of a $2 billion project to repair the aqueduct, a process expected to take eight months.

The backup water supply that will be tapped during the repairs is known as the Croton watershed. Unlike the Catskill-Delaware watershed, Croton’s water isn’t as pristine due to its proximity to suburban development, which introduces more runoff and waste. For this reason, Croton water must go through filtration, as mandated by the Environmental Protection Agency.

A map displays the locations of the Catskill and Delaware Watersheds, the Croton Watershed, and the Delaware Aqueduct, all within New York State.

In 2015, the Croton Water Filtration Plant opened in the Bronx. During the eight-month period when the Delaware Aqueduct is closed, this plant will ramp up its operations, although it can only produce about 25 percent of the city’s daily water demand.

To bridge the gap, unfiltered Croton water will be blended with water from the Catskills in a ratio of approximately one to three. This mixture will then flow into the city’s main reservoir.

This practice of “blending” can be contentious, said Sarah Meyland, a water expert based in Huntington, N.Y. “If you are mixing high-quality water with less-than-the-best water, the concentrations will be diluted in the supply,” she noted. “But that’s not to say you won’t have exposure to whatever is in the Croton water.”

Ms. Meyland added that microorganisms often found in many water sources might become present in the Croton-Catskill mixture. However, Paul Rush, deputy commissioner of the city’s Bureau of Water Supply, emphasized that all water—whether filtered or not—is rigorously tested and treated for harmful pathogens and contaminants using chlorine and ultraviolet light.

A recent project report mentioned that there could be “episodic taste and odor issues” related to the Croton water, which are being carefully monitored. While the Bronx filtration plant can remove impurities from Croton water through carbon filtration, the blend of Croton and Catskill water will rely on dilution to minimize any taste or odor issues.

Mr. Rush reassured that as the water from various sources and treatment facilities combines in the city’s pipes, any changes in flavor or smell would become less noticeable.

There’s another complication with the Bronx filtration plant, explained Bob Cooney, a retired quality engineer: The facility lacks backup power for its pumps.

Mr. Rush responded that, even in the event of a power failure, the system would continue to function using gravity. “We’ve looked at every contingency,” he stated.

Ms. Meyland, who has been closely following the plans for the Delaware Aqueduct’s closure, agreed that relying more on the Croton watershed was a prudent and necessary solution, given that the city and its surrounding areas use about 1 billion gallons of water every day.

Still, she acknowledged that reconfiguring the city’s water system poses a considerable technical challenge: “It’s kind of uncharted territory.”

{Matzav.com}