The water supply in Napier will be urgently chlorinated from today, after a positive test for E coli.
Napier City Council said even though the bacteria was detected at a low level, they would begin chlorinating the water from tomorrow morning as a precaution.
Napier mayor Bill Dalston said the council was taking the matter seriously and the water supply would be chlorinated for up to a month to get rid of whatever bugs were affecting it.
All of Napier, with the exception of Otatara and Puketapu, will be affected.
The council said people would not need to boil their water and the district health board was not reporting any increased incidences of illness.