A burst in Gisborne's main water supply pipeline is putting pressure on the city's reservoirs and residents are asked to urgently conserve water.
Contractors have spent the afternoon excavating the site and identified a joint fitting as the possible source of the leak.
The Gisborne District Council is warning the cleanout of the pipeline and repairing it could take until 2am tomorrow to complete.
Mayor Meng Foon told Newstalk ZB there are about two days worth of water left and the city needs to conserve water.
The council said staff are operating the secondary water supply at the Waipaoa Treatment Plant to supplement the city's water supply by early tomorrow morning.