5. NYC Tap Water is Unfiltered (Most of it)
Due to the high quality of water from the Catskill/Delaware supply, New York City is one of only five large cities in the nation that does not use filtration as a treatment method. It is actually the largest unfiltered water system in the country. Instead of filtration, NYC tap water that comes from the Catskill/Delaware supply is treated using chlorine and ultraviolet light. Chlorine is a disinfectant that kills germs and prevents bacteria from growing on pipes. Ultraviolet light further disinfects the supply. More than 2 billion gallons of water go through this disinfection process every day at the Catskill/Delaware UV Disinfection Facility in Westchester. Water from the Croton supply is filtered at an underground facility in the Bronx called the Croton Water Filtration Plant.
