Three water systems have tapped the Gihon Spring at various times in history (shown here, compare with photo of Hezekiah’s Tunnel). The oldest of these, shown in red, is known as Warren’s Shaft after its modern discoverer, Captain Charles Warren; it consists of a vertical shaft and tunnels that gave the people within the city protected access to the water of the spring, which lay outside the city wall. Because the Gihon Spring lies low on the slope, the Jebusites (and the Israelites later) could not include it within their city wall without exposing the wall’s defenders to possible attack from anyone on the slope across the Kidron Valley.
The next water system to be built was the Siloam channel, shown in blue. It served as an aqueduct that irrigated the adjacent fields through openings in the channel wall. Its position outside the city wall indicates that it was used during a peaceful period, so archaeologists suggest that it may date to Solomon’s time.