Grey District residents will have to continue to boil their water until at least Monday after a chlorine leak at the main water pumping station.
The Coal Creek Pump Station, near Greymouth, was shut down on Friday morning, after chlorine gas was detected.
Grey District Council said a faulty seal was repaired and the pumping station is now operating.
But manager, Mel Sutherland, said the boil water notice will remain in place until chlorine levels are back to normal in the water supply.
He said the council is following Ministry of Health water safety guidelines.