Napier Mayor Bill Dalton says he hates the idea of chlorine in his city's water, but understands the need for caution.

His comments came yesterday after the Hawke's Bay District Health Board and Napier City Council agreed to chlorinate Napier's Enfield Rd reservoir after routine testing returned a positive test for e-coli.

While national standards allow the council to wait for a second positive result before taking action, the council said given the "learnings" from previous water situations they have acted conservatively and immediately.

Napier mayor Bill Dalton said he had a "strong suspicion" the positive test result would be proven to be a false alarm.


"I have to say, I hate the idea of our water having chlorine in it but it's an essential safeguard," he said.

Mr Dalton said the Napier City Council was acting on the best advice from scientists and health officials.

"We have made the decision to chlorinate today. It's an absolutely precautionary decision. There is no health outbreak but we have got a test which we need to have confirmed and we're just erring on the side of caution," he said.

Hawke's Bay District Health Board chief medical officer Dr Nick Jones said if the water was contaminated authorities did not want to lose a day waiting for further testing to come back.

Dr Jones said he did not think there was a risk of something that would resist chlorine, such as giardia or cryptosporidium, being in the water; hence a boil water notice was not issued.

"A boil water notice is very dramatic and has a big impact on the community ... you want to have good reason to do that," he said.

Napier City Council chief executive Wayne Jack said the council did not know how long the Enfield Rd Reservoir would be chlorinated for.

"The New Zealand standards for drinking water don't require any action to be taken until after the second test but we're being precautionary and putting chlorine into the Enfield Rd reservoir and then we'll reassess once that second test comes back," he said.

The Napier City Council's website specifies two main reservoir systems in Napier; the Thompson Rd system and the Enfield Rd system.

The website states the balance of the city is served by the Enfield Rd reservoir system, which includes the Taradale reservoir, and supplies the bulk of the population.

Mr Dalton said there were some areas of Napier that would receive chlorinated water and some that wouldn't, although he couldn't specify which parts.

There have been no increased reports of sickness in the Napier area, however if anyone
was feeling sick with diarrhoea and/or vomiting that lives in this area they should see or call their health professional or call Healthline 0800 611 116.