From the Reservoir to the faucet: Where NY water supply comes from

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Before it hits your tap, unfiltered water from the Catskills winds its way through 6,000 miles of pipes aqueducts and tunnels.

Most of New York City's water -- 90 percent -- comes from the Kensico Reservoir. It holds 30 billion gallons and then travels to the ultra violet treatment facility in Westchester County, where 12,000 bulbs treat 1 billion gallons of water a day.

According to the DEP, UV rays treat the water for certain types of protozoa in particular, crypto sporidium, a microorganism that would give you stomach illness if they are not treated for and what the UV light does is take part of the genetic code and binds it together so they can’t replicate.

Then a team of scientists test the water to make sure there are not high levels of fecal chloroform bacteria from birds and other sources.

HILL VIEW Reservoir is the last stop before the water travels through three water tunnels through the five boroughs.

Ten million people are drinking this water from residents, commuters and visitors and people north of the city who draw from NYC.

Throughout the city, DEP scientists collect samples every single day from all five boroughs everyday, 365 days a year.

The city has 1,000 sampling stations that taps into the pipes outside your front door.

Before it gets to your tap, chlorine is added as a disinfectant and orthophosphate is added as a corrosion inhibitor to prohibit lead and metals from leeching.

New York City's unfiltered water system is a marvel of modern engineering because the water gets to you by gravity alone from the mountains all the way to the city.