Kurow residents have been advised to boil water while the cause of bacteria contamination in some of the town's pipes is investigated.
Waitaki District Council water services and waste manager Martin Pacey said chlorine was being added to the water and the council would flush the pipes to clear the contamination.
Residents might notice a small change to the taste and smell of the water.
Mr Pacey said the water monitoring would continue and once it was clear for three days the council would lift the boil water notice and advise residents water was safe to drink.
Most of the water supplies in New Zealand have low levels of chlorine in them to ensure any bacteria entering the pipes after treatment is killed.
However, Kurow water has not historically been chlorinated, leaving it vulnerable to this type of event.
