Warren’s shaft" is the underground waterworks dating from the age of the kings of Judea. The entrance crosses a tunnel descending to a vertical shaft, whose end lies on the level of the Gihon spring. "Warren’s shaft" is possibly the Jebusite water system that David used to conquer to city, but it is thought that the inhabitants of the lnd at that time lacked the technology to build such a work. The shaft enabled people to draw water from the Gihon spring without leaving the city, important in times of war, and was rediscovered in the last century by a British officer, Captain Warren.
2 Samuel 5
6 And the king and his men went to Jerusalem against the Jebusites, the inhabitants of the land, who said to David, “You will not come in here, but the blind and the lame will ward you off”—thinking, “David cannot come in here.” 7 Nevertheless David took the stronghold of Zion, that is, the city of David. 8 And David said on that day, “Whoever would smite the Jebusites, let him get up the water shaft to attack the lame and the blind, who are hated by David’s soul.” Therefore it is said, “The blind and the lame shall not come into the house.” 9 And David dwelt in the stronghold, and called it the city of David. And David built the city round about from the Millo inward. 10 And David became greater and greater, for the Lord, the God of hosts, was with him.
The Revised Standard Version, (New York: Oxford University Press, Inc.) 1973, 1977.