Longest water supply tunnel
Who
West Delaware tunnel
Where
United States ()
When
1944
The longest tunnel of any kind is the New York City West Delaware water-supply tunnel, begun in 1937 and completed in 1944. It has a diameter of 4.1m 13ft 6in and runs for 169km 105miles from the Rondout reservoir into the Hillview reservoir, in Yonkers, New York, USA.