The Mourne Conduit was a water main which ran 42 kilometres (26 mi) from the Silent Valley Reservoir to Carryduff, near Belfast and was built between 1893 and 1901 for the Belfast City and District Water Commissioners. This was supplemented by additional pipelines twice in the 20th Century. This system supplied water to Greater Belfast and North Down for more than 100 years. It is labelled as the Mourne Aqueduct in Ordnance Survey maps from the early 20th century.

The Silent Valley Reservoir is a reservoir located in the Mourne Mountains near Kilkeel, County Down in Northern Ireland. It supplies most of the water for County Down, surrounding counties and most of Belfast. It is owned and maintained by Northern Ireland Water Limited. The reservoir was built between 1923 and 1933 by a workforce of over 1,000 men, nine of whom died during construction.