The Hamilton City Council is being threatened with a judicial review after voting to resume fluoridating the city's water supply.
On Thursday, councillors voted 9-1 to resume fluoridation. The practice had been stopped last June, but a subsequent referendum was overwhelmingly in favour of its return.
The council was due to vote on the matter last year, but that was delayed while it waited for a High Court decision on a challenge to councils' legal right to fluoridate water. The challenge, in New Plymouth, was thrown out.
The Dental Association and the Waikato District Health Board support fluoridation but the campaign group Safe Water Alternative New Zealand is not happy with the decision and says it will seek a judicial review, as signalled in February.
Co-ordinator Trevor Crosbie said the council had breached the Local Government Act and further consultation should have happened before voting to reintroduce fluoride. He said he would be speaking with his lawyer in the next few days.
Fluoride Action Network spokesperson Mary Byrne supports a judicial review. She said people are uneducated about the dangers of fluoride and the councillors had not done their job in informing people about all the facts.
The DHB spent about $47,000 on a pro-fluoride campaign - $8000 of it on billboards and banners.
Communications director Mary Ann Gill welcomed the council's decision and said the sooner water fluoridation was resumed for children's oral health, the better.
But she said it was unfortunate the DHB had had to spend so much time and effort on the referendum when there were other major challenges. These included "the return of diseases such as measles, whooping cough and hepatitis B, which should have been eradicated in my lifetime with the benefit of immunisation."
Ms Gill said it would be unfortunate if a judicial review did go ahead, as more taxpayer money would have to be spent.
Hamilton mayor Julia Hardaker says she was aware of the possible review. "Councils across New Zealand are going through the same process as Hamilton has been through and I expect it isn't fully over yet," she said.
"I continue to believe this is a matter for the Government and the Government should make a decision for New Zealand on this issue."