That's not what I'm referring to. Yes, the water system is pressurized (as are all), but the tunnels themselves are ~500 feet below ground [1][2]. Water is pump

That's not what I'm referring to. Yes, the water system is pressurized (as are all), but the tunnels themselves are ~500 feet below ground [1][2]. Water is pumped to valve chambers which are themselves far (~250 feet) below ground, then again to the surface. The head pressure on a 500 foot column of water would be over 200psi. This article [3] says that the first leg of water tunnel three runs at over 300 psi, though, so maybe that's the answer. It just seems crazy. [1] https://en.wikipedia.org/wiki/New_York_City_Water_Tunnel_No._3#:~:text=upstate%20water%20supply.-,Water%20Tunnel%20No.,completed%20until%20at%20least%202026 https://en.wikipedia.org/wiki/New_York_City_Water_Tunnel_No..... [2] https://www.theverge.com/2013/10/19/4853636/underground-with-manhattans-new-water-tunnel-three-photo-essay https://www.theverge.com/2013/10/19/4853636/underground-with... [3] https://www.baltimoresun.com/news/bs-xpm-1998-08-21-1998233084-story.html https://www.baltimoresun.com/news/bs-xpm-1998-08-21-19982330...