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.
"Water from the Waipaoa Plant is 'harder' and people may notice a difference in taste, but it meets health standards and is absolutely safe to drink," it said in a statement.
"We continue to ask everyone to restrict their outdoor water use – no use of hoses or sprinklers to water your lawn or garden and no filling swimming pools.
"Conserving water for the next few days will be necessary as the repair is completed and the reservoir supply is restored."
Foon said once they've plugged the leak, they can turn the pipe back on and fill the reserves with dam water overnight.
The mayor is hopeful the repairs be completed quickly but in the meantime they're asking the community to conserve water.