Residents in Carterton have been told to boil all drinking water after E.coli was found in the town's water supply.
Carterton District Council says residents should expect the notice to remain in effect for at least seven days.
It comes just a week after a previous boil water notice in the town was lifted. That one was issued after a potential faulty valve resulted in a low E.coli bacteria reading in the town's supply.
However despite repairing the valve and increasing the flushing regime by 50 percent, the council received a low-level E.coli reading in one of its sampling points on Thursday.
"The drinking water standard for New Zealand requires E.Coli levels to be less than 1 MPN/100ml (Most Probable Number)," the council said in a statement.
"Today's sample reading was at 1 MPN/100ml. The risk to the community is extremely low but the council is taking a precautionary approach."
Dave Gittings, the council's infrastructure, services and regulatory manager, said it was disappointing to receive another low-level reading.
"We do appreciate how frustrating this will be for our residents over the long weekend.
"We have alerted the District Health Board and the local medical centre as a precaution and we are taking all steps necessary to keep our community safe."
He said water was available outside the Carterton Event Centre.
Anyone experiencing diarrhoea, vomiting and/or a fever was advised to get advice from their doctor or contact Healthline on 0800 611 116.
The boil notice applies to all water being used for drinking, making baby formula, juice, ice, washing fruit and vegetables, other food preparation/cooking needs, or brushing teeth.