See Amihai Mazar, “Jerusalem’s Water Supply in the First Temple Period,” in Shmuel Ahituv and Benjamin Mazar, eds., The History of Jerusalem: The Biblical Period (Jerusalem: Yad Ben Zvi, 2000), p. 197 (Hebrew). The actual flow varies greatly, from about 700 to 4,750 cubic meters per day, depending on annual precipitation; Alon De Groot, “Water Systems in Jerusalem in the First Temple Period,” in Donald Amit and Rivka Gonen, eds., Jerusalem in the Time of the First Temple (Jerusalem: Yad Ben Zvi, 1991), p. 124 (Hebrew).