A suspected e-coli outbreak has forced Hutt City Council to temporarily close the Naenae reservoir.
The council notified Regional Public Health yesterday about the likely presence of the bacteria that can cause diarrhoea. It was described as a low-level contamination and of low risk to the public.
The council's infrastructure general manager Bruce Sherlock said the water supply, which would be coming from an alternative site at the Waterloo treatment plant, would be chlorinated during the next few days.
While residents may notice some changes to the water odour and taste, the council had been "prudent" in temporarily changing to the safe-to-drink chlorinated water, Mr Sherlock said.
The reservoir would be drained over the next three days to confirm the source of the contamination.
Residents who want to continue using unchlorinated water could fill containers at Te Puna Wai Ora, the water feature in Buick St, Petone.