The organisation which challenged the South Taranaki District Council's decision to add fluoride to its water supply says a High Court judge has got it wrong.
The court has thrown out the challenge from lobby group New Health New Zealand.
New Health argued that the council has no legal power to add fluoride to its water in Patea and Waverley, and that in doing so, it was a breach of the right to refuse medical treatment.
However, Justice Hansen ruled there is implied power under the Local Government Act for councils to add fluoride to drinking water and that no further consent is required from the Minister of Health.
The judge also ruled that whilst he accepted fluoridation has a therapeutic purpose, it does not constitute medical treatment.
New Health chairman Dave Sloane says he thinks the judge has got it wrong and they will be appealing against the decision.
The national co-ordinator of another group opposed to fluoridation, Mary Byrne of the Fluoride Action Network, told Radio New Zealand's Checkpoint programme the ruling sets a dangerous precedent.
"The judge has said that it's legal because water is not a food for the purposes of the Medicines Act. So does that mean that councils can add anything they like to the water supply and it won't come under the Medicines Act, particularly things that may occur naturally, such as lithium. Is it kind of open slather for councils just to add what they feel like putting in the water?"