The central drainage channel of Second Temple Jerusalem is an archaeological site in Jerusalem. It is a large drainage tunnel or sewer that runs down the Tyropoeon Valley and once drained runoff and waste water from the city of Jerusalem during the later part of the Second Temple period. The channel is about a kilometer in length. According to Leen Ritmeyer, the drain is mainly of Hasmonean age, with the exception of a bypass section near the southeast corner of the Temple Mount, which is Herodian.
The walls of the channel are made of heavy slabs of stone. Manholes with round, stone manhole covers are spaced along the length of the channel. Some of the original plaster is intact. Pottery and coins found in the water channel confirm its date.
The water channel has been identified as the water channel described in Josephus Flavius' "The Wars of the Jews". According to Josephus, in the year 70 CE thousands of Jerusalemites took refuge from the Roman sacking of Jerusalem inside this water channel. Archaeologists attribute ash on the walls of the channel to fires set by the Romans attempting to force the Jewish survivors out of the channel.
Sections of the ancient road built along Jerusalem's central, or Tyropoean Valley, and the drain tunnel underneath it were first discovered by Charles Warren and Charles Wilson in 1867-1870. Prof. Frederick J. Bliss and Archibald C. Dickey of the Palestine Exploration Fund excavated parts of the road between 1894 and 1897. The find was reburied when their excavation concluded. Other sections were uncovered, then reburied, by later archaeologists, Jones in 1937 and Kathleen Kenyon in 1961–1967.
The tunnel was rediscovered in 2007 by archaeologists Ronny Reich and Eli Shukron who were excavating the Herodian stepped street leading up from the Pool of Siloam towards the Temple when they happened on the water channel. Their excavations have eventually made accessible much of the length of the road between the Pool of Siloam and the south-eastern corner of the Herodian Temple Mount.