Water Tunnel No. 3

By Deane Barker on July 25, 2005

Water Tunnel No 3 IN NEW YORK CITY: Here’s an interesting article on the construction of Water Tunnel Three underneath New York City. Not surprisingly, it’s a tunnel that carries water. This seems a little elementary, but how else do you get water to 9 million people every day?

New York City is currently served by two tunnels — each between 15 and 17-feet in diameter that are both over 60 years old.

I saw a documentary once that mentioned that either tunnel would instantly collapse if not for the water pressure pushing outwards (meaning, don’t ever shut off the tap upstream). This means the tunnels can’t be repaired, because they can’t cut off water to the city for any period of time nor can they risk collapse. It’s a tense situation — the use of the tunnels is the only thing that keeps them…usable.

The third tunnel is a 50-year construction project. They started it in 1970, and it won’t come online until 2020. The tunnel is 24-feet in diameter, so if you compare its area to the other two:

  • Water Tunnel One: 176 feet
  • Water Tunnel Two: 227 feet
  • Water Tunnel Three: 452 feet

If my math is correct — and everything else being equal — this tunnel will more than double the water delivery capacity of the city, meaning they could try and repair the two existing tunnels. Tunnel Three is planned to carry 1.6 billion gallons of water every day.

Not surprisingly, it’s no small undertaking:

Water Tunnel No. 3 is by far the largest construction project in New York City’s history. When completed, it will extend 60 miles through Westchester County, the Bronx, Manhattan, Queens and Brooklyn.

To put that in perspective, that’s twice as long as the tunnel under the English Channel. Additionally, Water Tunnel Three will run between 250 and 800-feet below the surface, while the Channel Tunnel is only about 150-feet below the sea bed. And keep in mind that all this digging happening below one of the largest cites in the world.

No wonder it’s priced at a mere $6 billion.



  1. 1.6 billion gallons? That’s a lot of water! I wonder how that compares to the flow of some good sized rivers.

    The NYC DEP website has a lot of info on the watershed areas that feed into that water system. I’ve never tasted NYC water, but from the sound of it, that water system is known for the high quality of the water they produce. Plus they distribute the water to a very large area outside of NYC.

    Thinking about the tunnels that feed into the system reminds me of a news story I read while in Michigan last week; a woman was scuba diving in Lake Michigan and got sucked into a water inlet pipe that feeds the cooling system for a power plant. She went a half mile through the pipe & ended up with only a bloody nose. Here’s a link to a news article about the incident.

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