Central Hawke's Bay District Council is warning water could run out in Waipukurau and has issued urgent level 4 restrictions.
The council said there is a "major leak" leak in Waipukurau's drinking water network.
The Pukeoroa reservoir is at a "critical low level". It was sitting at 40 percent capacity at 6.30am and dropped to 26 percent in a matter of hours.
In an update at 9:05, the council said thanks to Waipukurau residents, the reservoir has reached 30 percent, however to be at a safe level, this must get up to 60 percent.
"We can currently make 60 litres of water per second and are currently using roughly 230 litres."
The council said they have confirmed that there are no other breakages across the network with the Porangahau Road break being the cause of the sudden loss.
There is a risk a boil water notice will be applied if water use does not significantly reduce but the council is asking that people remain calm and dont panic buy water.
They have said there will be enough for everyone as long as people remain sensible about their water consumption.
The council is asking people to only use water for emergency purposes, not to use their dishwashers or washing machines, limit showers to two minutes and to only flush the toilet if truly necessary.
The level four restriction is expected to remain in place until this evening to allow the reservoirs to recover.
