The Greater Wellington Regional Council operates four water treatment plants located in the Hutt Valley (Te Marua, Waterloo, Gear Island and Wainuiomata). These plants supply water for use in Upper Hutt, Lower Hutt, Porirua and Wellington cities.
Wellington city's water supply contains added fluoride for dental health, mainly for the benefit of young children.
The natural level of fluoride in Wellington's water is around 0.1 milligrams per litre or parts per-million (ppm). The Ministry of Health recommends water suppliers adjust the fluoride amount to between 0.7 and 1.0 ppm.
The fluoride is added at the GWRC water treatment facilities at the Te Marua, Wainuiomata and Waterloo treatment plants.
The guidelines from the Ministry of Health state that there are no significant health concerns associated with water fluoridation at the optimal level for dental health, and the Council follows these guidelines.