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Fluoride at water treatment plants

We operate four water treatment plants in the Wellington metropolitan area on behalf of Greater Wellington Regional Council  who own these water treatment plants.   


These are:

Wellington region

  • Te Marua Water Treatment Plant
  • Wainuiomata Water Treatment Plant
  • Waterloo Water Treatment Plant
  • Gear Island Water Treatment Plant


We add fluoride to the water at the Wellington metropolitan treatment plants.

Our aim is to maintain a steady level of fluoride in the water at treatment plants that meets the Ministry of Health fluoride target of 0.7 – 1.0ppm. This is the amount recommended by the Ministry of Health and the World Health Organisation to provide protection against tooth decay.

We also have controls in place to ensure we never supply consumers drinking water over the Maximum Acceptable Value (MAV) of 1.5ppm.

Stopping fluoride at Te Mārua and Gear Island Water Treatment Plants

In 2021, we stopped the fluoride facilities at the Te Mārua Water Treatment Plant in May and at the Gear Island Water Treatment Plant in November due to operational and health and safety issues, which meant we could not guarantee that we could add fluoride safely. At the time we didn’t tell anyone we did this, and we apologise for that, and the concern caused.

In March 2022, we announced that the fluoride facilities at both Te Mārua and Gear Island had been stopped but we provided people with an incorrect date for when we stopped fluoridation at the plants, which we corrected the next day. Again, we acknowledge that this falls short of the expectations of our customers and communities, and we apologise for the concern caused.

To fully understand why the fluoride facilities were turned off at the Te Mārua and Gear Island Water Treatment Plants and why our customers, community, Councils and our Board were not told of this in a timely and accurate manner, the Wellington Water Board commissioned an independent inquiry in March 2022.

The inquiry was undertaken by MartinJenkins and completed in late June 2022. The Board received and accepted all the inquiry’s recommendations in early July 2022. 

In November 2022, the Board formally closed out the inquiry after all the recommendations were implemented.

Restoring fluoride in the drinking water

We have worked at pace to safely restore fluoride at both plants. To do this we constructed two new fluoride facilities at Te Marua and Gear Island and in September 2022 these facilities were operational and reliably fluoridating the drinking water within the Ministry of Health target range.

As part of this work, we are also looking at improvements to the fluoride facilities at the Waterloo and Wainuiomata Water Treatment Plants to improve the consistency and reliability of fluoride levels at these plants. 

Every month we publish the average fluoride levels at each of the metropolitan Wellington water treatment plants