After a year of water woes in Hawke's Bay, a funny taste has been left in the mouths of its residents - chlorine.

This is a taste residents will probably have to get used to, with it unlikely the region's water will ever be treated the same again.

The treatment is expected to course through the water supplies of the twin cities for the foreseeable future, in light of heightened awareness about water quality following the 2016 Havelock North Water contamination, and recommendations from the Government Inquiry into the outbreak.

"The way we view water has changed completely," Hastings Mayor Sandra Hazlehurst said.

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"The Havelock North water contamination must never be repeated anywhere in NZ and the Government Inquiry is now strongly recommending that all public water suppliers to treat all water supplies to protect public health.

"This is a change to protect our people which is most important to me."

Chlorine first entered a Hawke's Bay water supply in August 2016, as a precaution against a bug in Havelock North which had caused a thousands of people to fall ill.

More than a year on its presence is still noted, while the outbreak which caused its first introduction into the water supply has meant the mandatory treatment of all public drinking water supplies in New Zealand has been proposed.

As well as continued chlorination, Hastings District Council has given the green light to a long-discussed $12 million work programme which would involve shutting down Brookvale Bore 3 for good, identifying potential new water sources and enhancing the network overall.

Mrs Hazlehurst said she hoped this showed residents that the health and wellbeing of the community would remain the council's top priority.

"Therefore the delivery of safe drinking water all the way to the tap is paramount to us," she said. "The work we are undertaking in terms of investment in new infrastructure and resources is all part of our wider water strategy and demonstrates our strong safety commitment to our people."

Although chlorine has been an unpopular addition, she said it provided the extra precaution of disinfecting water through the network to taps.

"Chlorine has been used around the world for more decades to disinfect water to make it safe to drink. It kills the water-borne organisms that can make us sick and is safe when used at the approved levels.

"We have installed chlorine removal taps in a number of areas within our community for those who wish to take up this option. People also have the option of installing filters in their homes if they wish."

The council was criticised in the Inquiry's stage 2 report. The report put the Hastings council on notice about several issues it considered had not been dealt with adequately or in a timely enough manner since its stage 1 findings in December last year.

Napier

Despite the Hastings event being internationally unprecedented, the regional focus shifted to Napier early in 2017 - with transgressions throughout the year.

Heightened awareness of water quality meant the moment E. coli was detected in the Art Deco City's water supply at the Napier City Council's Enfield Rd reservoir in February, the supply was chlorinated.

Although treatment was stopped, this did not last long. In May another positive reading of E. coli was found, this time at a Park Island site.

This was expected to last a few weeks, but instead it didn't end, with chlorine continuing to stream through pipes as the council rolled out a "comprehensive programme of work" to improve the supply.

Napier Mayor Bill Dalton said the number of water-related incidents in the city this year had been the result of a new testing regime, with drinking water criteria tightened up "quite dramatically" since the Havelock North contamination.

"So it's inevitable that we will have more events.

"I hate chlorine in the water but the end result is that we are required as a council to deliver to our ratepayers a safe water system, and we've increasingly been told the way to do that is by having a chlorinated water supply."

He said he doubted the "purity" of Napier's water and its management could ever return to the way it was.

"My view is that with the findings of the Havelock North inquiry we will eventually be told that all drinking water, all water supplies in households will have to be chlorinated. I don't think there's any doubt about that."

"You can rest assured I would love it to [be pure], but I don't think we're going to be allowed to do that."

The council is currently behind on nine of the 28 items on its work programme, which is expected to take several years to complete and included the inspections of 11 reservoirs and a full bore-head water-quality review.

In light of the Inquiry report, Napier ratepayers are also faced with the prospect of a rate increase, with the council proposing $9.5million worth of water projects, which may need to be undertaken as part of its Long Term Plan 2018-2028 to bring Napier's water into line.

"At the end of the day if the authority says this has to be done, then we have to find a way of doing it," Mr Dalton said.

"My view is whenever there's an issue, there's always an overreaction. My personal view is that this is an overreaction, but having said that if they're the rules then our role as a council is to adhere to the rules in the most efficient manner possible."

In November, the council announced chlorine would remain in Napier's water for the foreseeable future. But the year was not over yet - in December chlorine was added to more of Napier's water supply following another positive E. coli reading - this time at the Otatara reservoir.

Napier and Hastings councils are among those in the region which have banded together as part of a Hawke's Bay drinking water governance committee.

Its aim was to provide governance oversight to the Joint Working Group established late last year to drive greater collaboration between the agencies on water safety matters.