Local Government Minister Nanaia Mahuta has led a huge overhaul of water provision that could see regional bodies in charge of supplies. (Video first published in November 2018)

The Christchurch City Council has quit Water New Zealand over concerns about the group's "agenda" to promote mandatory water treatment.

Councillors have been battling to keep Christchurch's water free from permanent treatment since the Government initiated a clampdown on unprotected water sources following the 2016 Havelock North incident when a contaminated aquifer left four dead and 5500 ill.

The council has repeatedly voiced its opposition to what it sees as Water New Zealand's promotion of chlorination, regarding the organisation as little more than a lobby group for the water treatment industry.

STACY SQUIRES/STUFF Officials in Christchurch are leading a multi-million dollar programme to upgrade the city's well heads after the drinking water system was found to be vulnerable.

Now, in a move councillors say marks a major line in the sand, it has withdrawn its membership of the industry body.

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While the council – which has brought in temporary chlorination during a major programme to improve infrastructure – has distanced itself from the organisation, staff are free to retain their personal affiliations.

John Mackie, who as head of three waters and waste is one of the council's most senior advisers on water issues, is on the Water New Zealand board.

MARNEY BROSNAN Water NZ chief executive John Pfahlert believes the Ministry of Health should be stripped of its role in water regulation.

Mackie is currently suing former Christchurch mayor Garry Moore for $500,000 over claims Moore defamed Mackie in comments made about his dual roles.

Another recently elected Water New Zealand board member is Iain Rabbitts, whose contract was terminated by the council in controversial circumstances in May after he raised concerns about a programme to fix substandard well heads.

Explaining the decision to terminate the membership in a report to councillors, council chief executive Karleen Edwards said it was based on a "misalignment" in the directions the council and Water New Zealand wanted to take.

She said staff had benefited from training, conferences and peer networks during the council's many years of membership.

"The advocacy of Water NZ for a one size fits all proposal for delivering and managing water services is clearly seen as misaligned with Christchurch City Council's direction and the aspirations of our communities."

Water New Zealand says it is not a lobby group for the water treatment industry.

Iain McGregor Christchurch City Council chief executive Karleen Edwards said the authority is distancing itself from Water New Zealand over differing approaches to water management.

At a conference in August chief executive John Pfahlert said its only role was to "provide good, technical advice to water service managers" and that it did not promote any particular view.

He said on Wednesday: "It is up to individual organisations to assess the value and benefits of having corporate membership of Water New Zealand.

"The majority of councils and water utilities in the country do have either corporate membership or staff who are members."

Cr Deon Swiggs said the decision had been made with "support and direction" from the council, and that it was a "major stand … against the one-size-fits-all agenda of Water NZ".

"[It] wants to establish a regulated water industry and force the option of chlorination onto all water suppliers in the guise of public health.

"There are other ways, and proper investment into the infrastructure is a far better option and as we have good quality water under us that should also be part of the solutions."

SUPPLIED Christchurch's drinking water is currently chlorinated for the first time since the 2011 earthquake after wells were found to be defective. (File photo)

Vicki Buck welcomed the council's withdrawal: "We clearly don't support Water NZ's views on mandatory chlorination, mandatory fluoridation, or taking water functions off the city council and making it part of some huge separate authority."

Pauline Cotter, who chairs the council's infrastructure, transport and environment committee, said Water New Zealand's "push for mandatory chlorination … does not align with our strategic directions that councillors have set, of high quality drinking water".

"We are strong in the belief that we have robust measures in place to ensure that our drinking water is of high quality and is good to drink, and do not wish to be subject to a one-size-fits-all mentality," she said.