During times of siege this spring inside a cave, supplied water to the inhabitants of Jerusalem via a tunnel and a shaft through which water could be drawn without the enemy's knowledge.
This fresh water underground spring supplied 200-1,100 cu. metres daily. In addition to the tunnel, there were several open canals nearby, extending southward, that carried the excess spring water to the fields and gardens along the Kidron riverbed.
In early biblical times, this spring was outside the city beyond the wall. When the city was besieged, the inhabitants were in danger of being cut off from their water supply. Therefore in the eighth century BCE, Hezekiah had a tunnel excavated from the spring to the pool of Shiloach which was inside the city at that time. (II Kings ch. 20 v. 20).
Gichon is mentioned in connection with Shlomo (Solomon) who was brought there to be anointed king. 'And Zadok the priest and Nathan the prophet have anointed him king at Gichon and they are come up from there rejoicing so that the city rang again'. (I Kings ch 1 v. 45)
