Pontius Pilate and the Jerusalem Aqueduct

Recent archaeological work, published in the journal Geoarchaeology, has shed light on the history of a large segment of Jerusalem’s ancient aqueduct. The section, known as the Bier Aqueduct, is a roughly 3-mile-long underground segment of the ancient water system. Carbon-14 dating led the team from Hebrew University to suggest that the Bier Aqueduct was likely constructed during the reign of the Roman governor Pontius Pilot (c. 26–36 C.E.), who infamously oversaw Jesus’s execution.

Exploring a narrow section of the aqueduct.
Credit: Y. Negev

The archaeological survey was conducted by spelunking into the dark and murky waters of the Bier Aqueduct to map as much of its course as possible. During the survey, the team documented the various methods used in its construction and took several radiocarbon samples from the plastered walls. Analysis of the samples indicates the aqueduct was likely built in the early first century C.E. and was refurbished in the second century after the destruction of the Jerusalem Temple. As such, the team suggests that the Bier Aqueduct could be the same aqueduct attributed to Pontius Pilate by the Jewish historian Flavius Josephus. According to Josephus, Pilate used money from the Temple’s treasury to build the aqueduct, which led to riots in the city (Antiquities 18.60–62). Despite several aqueducts feeding into the Temple area, the Bier fed into the upper city where the governor’s palace would have been located, thus perhaps explaining Josephus’s reference to the riots that broke out across the city.

Pontius Pilate and the Jerusalem Aqueduct examining transition

Azriel Yechezkel examining the aqueduct of Pontius Pilate.
Credit: Y. Negev

The aqueduct, which begins at the Bier spring, includes five different sections, each playing a role in collecting, channeling, and controlling water. The aqueduct’s architecture is unique within the land of Israel and would have been one of the most technologically advanced water systems of the Roman world. Although the aqueduct took water directly from the Bier spring, its design also allowed for the capture and diversion of ground and surface water, thereby providing Jerusalem with more than seven times the annual discharge of the Bier spring alone.

Pontius Pilate and the Jerusalem Aqueduct roof

Investigating a transition in the aqueduct roof.
Credit: Y. Negev

According to the researchers, the aqueduct’s engineers must have “mastered several fields of hydrogeology, hydraulics, and water‐harvesting techniques.” Each of the five sections of the aqueduct featured specific roof designs that were “intended to overcome the physical/hydraulic loads exerted on the tunnel.” In sections of the aqueduct where the bedrock was stable, the entire tunnel was hewn directly into the rock. In areas where the bedrock was weaker, the tunnel was built as a trench with a complex roofing system to protect against collapse. Along the tunnel was a system of shafts that provided access to the surface. These shafts assisted in both the construction of the tunnel as well as maintenance. Measures were also taken to closely control the flow of water, especially during the rainy season when the aqueduct might suffer damage from flooding. This incredibly complex system bears witness to the development of Jerusalem and the surrounding area during the time of the Roman governors, including Pontius Pilate.

Jerusalem lies at the heart of Biblical archaeology. In the free eBook Jerusalem Archaeology: Exposing the Biblical City, learn about finds in the Biblical world’s most vibrant city.

Throughout its long history, Jerusalem has always had a major problem 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 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 Jerusalem’s aqueduct was built to bring in water from more distant sources. The dating of the aqueduct system, however, has been much debated and, as such, this new study provides additional clarity on the development of the ancient city of Jerusalem.