People in Hanmer Springs are being told to boil their drinking water.
Hurunui District Council has found potentially infectious E.coli bacteria in the town's supply.
It said all council-supplied drinking water, including water used for food preparation and cleaning teeth, must be boiled for at least one minute before it could be safely used.
The notice applies for at least 10 days, as the council needs three clear test samples before lifting the warning.
