Gisborne District Council is warning that the city's water supply could run dry in three days if water is not conserved.
The city's main water supply was cut near the main reservoir at Mangapoike on Monday night, following a 50-metre-long hillside slip that burst a pipe.
The council's chief engineer, Peter Higgs, says the city is now relying on two smaller water supplies from the Te Arai Bush catchment and the Waipaoa River, but that's not enough to last for long.
He says it could be at least two weeks until full supply is restored.
All non-essential water use, such as hosing, sprinkling or refilling swimming pools, is now banned and Gisborne mayor Meng Foon says council staff will be out on the streets enforcing the ban.