Gisborne District Council says it has only about 24 hours of water supply in its reservoir after a leak in the main water supply pipeline.
The council earlier today imposed a total ban on all outdoor water use, meaning no car washing, lawn or garden watering or filling swimming pools.
Contractors are now onsite at Makaraka in Gisborne digging to find the leak.
They needed to identify all the underground services before they could begin to dig, the council said.
"We won't know the cause of the leak until they reach the pipe," the council said.
"Water is still available to all households and commercial properties in the city, but drawing from reservoir storage which have enough for approximately 24 hours.
"We urge people to stop using water outdoors for non-essential use."
The council said it doesn't know how long the restriction will be in effect until it knows what's required to fix the leak.
The council says it will continue to update the public as more information becomes available.