So what did the residence of ancient Israel do to supply the city with enough water? They dug cisterns to catch as much rain water as possible. With a significant population and a religious center that required water, cisterns were an important part of the infrastructure. Any tour of Jerusalem will/should include a a chance to visit Warren's shaft, Hezekiah's tunnel and the newly discovered Pool of Siloam.
Today archaeologists are announcing the discovery of yet another ancient cistern in the city, and this is a big one. Take a look at the above picture to give you an idea of just how big it is. Here is what the press releases have had to say thus far.
The recently discovered reservoir, with an approximate capacity of 250 cubic meters, is one of the largest water reservoirs ever discovered from the First Temple period. Due to its size, archaeologists believe the reservoir was designed for and used by the general public.
According to Eli Shukron, the excavation director on behalf of the Israel Antiquities Authority, “the exposure of the current reservoir, as well as smaller cisterns that were revealed along the Tyropoeon Valley, unequivocally indicates that Jerusalem’s water consumption in the First Temple period was not solely based on the output of the Gihon Spring water works, but also on more available water resources such as the one we have just discovered."
Dr. Tvika Tsuk, chief archaeologist of the Nature and Parks Authority and an expert on ancient water systems, presumed that “the large water reservoir, which is situated near the Temple Mount, was used for the everyday activities of the Temple Mount itself and also by the pilgrims who went up to the Temple and required water for bathing and drinking."
You can read the whole article here.