Excavating the Jerusalem Aqueduct

Section of the Jerusalem aqueduct as seen from the air. Courtesy Alexander Wiegmann, Israel Antiquities Authority.

For much of the past 2,000 years, the Jerusalem aqueduct has provided water to the ancient city, with portions still used well into the 20th century. Now, excavations by the Israel Antiquity Authority (IAA) are uncovering this ancient water system. The IAA has uncovered a large section of the lower aqueduct in the Jerusalem neighborhood of Armon Hanatsiv, south of the Old City. The IAA intends to carry out conservation work on a portion of the aqueduct, which they will eventually interpret and display for the public.

Jerusalem’s Lower Aqueduct

Jerusalem’s lower aqueduct was one of many sections of the aqueduct built between the Hasmonean period (c. 140–37 B.C.E.) and the First Jewish Revolt (c. 66–70 C.E.). The lower aqueduct ran 13 miles from Solomon’s Pools, located south of Bethlehem, to the Temple Mount in the Old City of Jerusalem. It was one of the water system’s earliest sections and descends from Solomon’s Pools at a slight gradient of roughly 5 feet per mile. This amazing water system, initiated by the Hasmonean kings to increase the water supply to Jerusalem and in particular to the Temple Mount, continues to astound archaeologists today. Due to the aqueduct’s ingenuity and quality, it continued to be used through the time of the British Mandate (1922–1948), when the wide-scale introduction of electric pumps finally rendered it obsolete.

According to Ya’akov Billig, an archaeologist with the IAA who researches the Jerusalem aqueduct, “Two aqueducts brought water from Solomon’s Pools, located between Bethlehem and Efrat to Jerusalem. It amazes us to think how they managed in antiquity to make the accurate measurements of elevation along such a long distance, choosing the route along the mountainous terrain and calculating the necessary gradient, all this without the modern sophisticated instruments we have today.”

Excavators uncovering the Jerusalem aqueduct. Courtesy Yaniv Berman, Israel Antiquities Authority.

History of the Jerusalem Aqueduct

Throughout its long history, Jerusalem has always faced problems with securing water for its inhabitants. During the Iron Age (1200–586 B.C.E.), the nearby Gihon Spring, along with a large reservoir and cisterns, was sufficient to supply the city’s relatively small population. Both Hezekiah’s Tunnel and the Siloam Pool were built by King Hezekiah in the eighth century B.C.E. to expand the city’s Iron Age water system. Towards the end of the Second Temple period, the city’s population grew dramatically, and the Gihon Spring was no longer able to provide enough water for the city. It was for this reason that the Jerusalem aqueduct was built to bring in water from more distant sources. The dating of the aqueduct system, however, has been much debated and many sections were added at different times. One of the last sections to be added to the Jerusalem aqueduct was the so-called Bier aqueduct, thought to have been constructed by the Roman governor Pontius Pilate in the mid-first century C.E.