Section of Jerusalem's Lower Aqueduct Found by Sewage Builders

This marvel of engineering by the Hasmonean kings only went out of use when supplanted by an electric pump a century ago.

Assaf Peretz, courtesy of the Israel Antiquities Authority

A section of Jerusalem’s Lower Aqueduct built by Hasmonean kings more than 2,000 years ago was recently discovered by a company building new sewage lines.

In fact the stone system remained operational from its establishment in roughly the 1st century BCE until around 100 years ago, says Ya’akov Billig, the excavation director on behalf of the Israel Antiquities Authority, which conducted a salvage dig at the spot. The system was found by workers for Gihon, the local Jerusalem water and sewage company.

The section of aqueduct leading water to ancient Jerusalem was exposed in the Umm Tuba quarter, near Har Homa.

In its entirety, the aqueduct was very long, about 21 kilometers, starting at the Ein Eitam spring near Solomon’s Pools, south of Bethlehem, the IAA says.

"An educated guess is that it was Alexander Jannaeus (also known as Alexander Yannai) who built it," Billig told Haaretz. Its construction would have required terrific manpower and resources – and was a huge feat of ancient engineering.

There are only 30 meters difference in height between the water's origin and Temple Mount, which meant the downward slope of the aqueduct had to be extremely gentle, and carefully calculated. "The water level falls just one meter per kilometer of distance," Billig stated.

During the first centuries of its existence, the water meandering down the aqueduct was in an open channel. Over the centuries, the aqueduct needed repairs and renovations. Then some 500 years ago, during the Ottoman period, a terra cotta pipe was installed inside the channel in order to better protect the water, the IAA says.

As modern Jerusalem expanded, the aqueduct's remains became part of the urban landscape, including in the Jerusalem neighborhoods of Umm Tuba, Sur Bahar, East Talpiot and Abu Tor.  It enters the Old City of Jerusalem by the Dung Gate and passes through to Temple Mount.

It served until about a century ago, when it was replaced by a modern electrically operated system, the IAA explains.

The Umm Tuba section of the aqueduct was documented, studied, and covered up again for the sake of future generations. Other sections of the long aqueduct have been conserved for the public in the Armon Ha-Natziv tunnels, on the Sherover promenade, around the Sultan's Pool and additional projects are planned whose themes include the Lower Aqueduct.