Health experts will look at reducing the chlorination of Lower Hutt's water supply as soon as tomorrow.

On Friday, Naenae Reservoir tested positive for the E.coli bacteria, but further testing has found no E.coli in the water.

Wellington Water spokesman Alex van Paassen said the water was immediately chlorinated.

He said prior to Havelock North's outbreak they would have waited 24 hours for a second test to make that decision.

Van Paassen said all going well, today will be the third consecutive day the water's tested negative for E-coli.

If that's the case, authorities will meet tomorrow.

"We'll sit down and have a discussion with Regional Public Health, and if they're happy that everything's been carried out how it should have, then we'd look to start backing off on the chlorination."

Meanwhile, Napier City Council will continue to chlorinate its water while it conducts further tests on the Enfield Road reservoir.