Jerusalem's expansion in the late Second Temple period increased the demand for water. The sacrificial cult on the Temple Mount, and the masses of pilgrims who poured into the city, also required huge quantities of water. The Gihon spring and cisterns in houses, which in earlier periods had sufficed, were now supplemented in various ways. A series of enormous open pools or reservoirs that surrounded the city not only stored water but also created defensive barriers (like a moat). On the north side of the city these pools included (from east to west) Birket Isr'il (the pool of Israel) at the northeast corner of the Temple Mount, the Sheep's pools (or Bezetha or Bethesda pools; see John 5:2—4), and the Struthion pool (associated with the Antonia fortress). To the west (from north to south), were Hezekiah's pool (the Amygdalon pool or pool of the Towers, by Herod's three towers), the Mamila pool (outside the modern Jaffa Gate), and the Sultan's pool (in the Ben-Hinnom valley). Another large pool (Birket el-Hamra) was located near the junction of the Kidron, Tyropoeon, and Ben-Hinnom valleys.
The Temple Mount literally was honeycombed with rock-cut cisterns that stored water used by the cult. These cisterns were filled with rain water as well as by means of aqueducts that brought the water from sources outside the city. The earliest aqueduct apparently was constructed by the Hasmoneans, and the system was expanded by Herod. The aqueducts brought water from large collection pools (called Solomon's pools) south of Bethlehem, where the Judean mountains are higher in elevation than in Jerusalem. Water that was collected and stored in Solomon's pools flowed (by gravity) through channels and tunnels to the Temple Mount (a distance of about 13 miles). This water system is similar to the one at Qumran (although the water came from collection pools rather than flash floods), but is much larger in scale.
Recommended Reading
Nahman Avigad, Discovering Jerusalem (Nashville: Thomas Nelson, 1993).
Oleg Grabar and Benjamin Z. Kedar (eds.), Where Heaven and Earth Meet: Jerusalem's Sacred Esplanade (Austin: University of Texas, 2009).
Lee I. Levine, Jerusalem, Portrait of the City in the Second Temple Period (538 B. C.E.-70 C. E.) (Philadelphia: Jewish Publication Society, 2002).
Benjamin Mazar, The Mountain of the Lord, Excavating in Jerusalem (Garden City, NY: Doubleday & Company, 1975).
Emil Schiirer, The History of the Jewish People in the Age of Jesus Christ, Vols. 1-3 (Revised and edited by Geza Vermes, Fergus Millar, and Martin Goodman; Edinburgh: T & T Clark, 1986).