Water fluoridation is when the natural fluoride level in our water supply is topped up with just enough fluoride to help protect our teeth from decay.

Everyone with their own teeth benefits from having fluoride in the water.

Water fluoridation is supported by international, national and local health organisations and there is more than 60 years of extensive scientific study to support its safety.

The vast majority of medical and dental experts recommend water fluoridation because:

  • Water fluoridation is safe. The science is clear that the level used for water fluoridation in New Zealand is safe.  Too much of anything that the body needs, like salt, sunlight or fluoride, can cause harm.  There is no risk of getting too much fluoride from drinking fluoridated water.
  • Water fluoridation is effective. Sixty years of research shows that water fluoridation helps prevent tooth decay.  Along with brushing twice a day, choosing low sugar foods and drinks, and having regular dental checkups, water fluoridation helps to protect our teeth and provides lifelong benefits.  The NZ Oral Health Survey (2009) showed that children and adolescents in fluoridated areas had, on average, 40% less tooth decay than those in non-fluoridated areas.
  • Water fluoridation is natural.  When fluoride, in the form of hydrofluorosilicic acid, is added to water it is the same as naturally occurring fluoride.
  • Water fluoridation is fair. Everyone with their own teeth benefits from water fluoridation, especially the young and those who find it more difficult to afford dental care and checkups.
  • It's about community. If we do not have water fluoridation, our children and especially those disadvantaged in our community will suffer more tooth decay.  It is our duty to help look after the health of everyone in our communities.

The Health (Fluoridation of Drinking Water) Amendment Act 2021 shifted the decision-making authority on community water fluoridation from local authorities to the Director-General of Health on the basis that it is a health-based decision.

Recommended links and references for further information on the safety and effectiveness of fluoridation:

Answering common questions

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What is fluoride?

Fluoride is a naturally occurring mineral that is found in water, air, soil, plants, and lots of foods (such as seafoods and tea).

How does fluoride help our teeth?

It helps prevent decay by making teeth stronger, more resistant to tooth decay and by helping fix early stages of decay.

What is water fluoridation?

Water fluoridation is when naturally occurring fluoride is topped up to the best (optimal) level that helps protect teeth, which is between 0.7-1.0mg/L (sometimes also called parts per million, ppm).

Why do we need water fluoridation?

Most of New Zealand's drinking water sources are naturally deficient in fluoride and are below 0.7mg/L so there is not enough fluoride present to protect teeth.

Water fluoridation is a safe, simple and effective way to help prevent and reduce tooth decay for the whole community.

Tooth decay can have a big impact on our lives - affecting how we feel about ourselves when we smile, how well we can speak and chew, and how well we eat. Untreated decay can cause pain, tooth abscesses or serious infection. Treating decay can also be expensive. The 2009 New Zealand Oral Health Survey found that 44% of adults had avoided dental care due to cost in the previous year.

Who benefits from water fluoridation?

Water fluoridation benefits everyone with their own teeth, including children, older people, and those who find it hard to afford dental care. Even people on tank water can benefit from water fluoridation when they drink water, food and beverages from areas with water fluoridation.

Why do we need water fluoridation, when toothpaste already has fluoride and we clean our teeth twice a day?

Water fluoridation does not replace using fluoride toothpaste, brushing teeth twice a day, regular dental checkups, or eating a healthy diet low in sugar. These all work together to help protect our teeth.

The 2009 New Zealand Oral Health Survey found:

  • 63.5% of children (aged 2-17 years) brushed their teeth twice a day.

  • 65% of adults brushed twice daily with fluoride toothpaste.

So putting fluoride in the water supply ensures everyone is covered and given some protection.

For recommendations about using fluoride toothpaste, click here.

Does water fluoridation work?

Yes! Water fluoridation benefits everyone, especially children and teenagers.

The 2009 New Zealand Oral Health Survey found that:

Children and teenagers living in areas with water fluoridation had on average 40% less tooth decay than those living in areas with no water fluoridation.

"… children and adults living in fluoridated areas had significantly lower lifetime dental decay experience (ie, lower decayed, missing or filled teeth) than children and adults living in non-fluoridated areas … The difference is found despite the fact that the majority of people brush their teeth with fluoridated toothpaste" (p293).

These findings are consistent with international research and other New Zealand studies and data.

Read here about the experience of a Taranaki dentist who tells of the difference that community water fluoridation made to his dental practice.


Which areas in the Bay of Plenty and Lakes districts have water fluoridation?

In the Bay of Plenty area, Whakatāne and Ōhope currently have a community water fluoridation programme.

The level of naturally occurring fluoride in the Whakatāne River (which supplies the Whakatāne and Ōhope water supply) is around 0.12mg/l.  At the water treatment plant this is topped up to 0.7mg/l which is in the optimal range to provide the best protection for teeth.

In the Lakes area, Turangi and Taupō township water supplies are fluoridated.

The source of fluoride used is hydrofluorosilicic acid and it is the same as naturally occurring fluoride when dissolved in water. It is added during the water treatment process.

In New Zealand not all water supplies are able to be fluoridated, even if the council has public support to do so. This is due to a variety of reasons such as the technical complexities involved at smaller water treatment plants, as well as the fact that water fluoridation is not as cost effective for areas with under 750-1000 people.


Where else has water fluoridation?

About 370 million people around the world in 27 countries have fluoridated water supplies, including Australia, Canada, Ireland, Israel, Argentina, Singapore, Spain, the United Kingdom, and the United States. In addition, an estimated 40 million people drink water with naturally occurring fluoride at the optimal level.

Many European countries and some Central and South American countries with naturally low levels of fluoride in water sources use fluoridated salt.  Milk fluoridation schemes also exist in several countries. In some countries water fluoridation is not practical due to the complex and very old water systems without a single point to add fluoride.

Is there a 'down side' to water fluoridation?

Water fluoridation costs about 50 cents per person per year.  Everyone benefits from water fluoridation, especially children and adolescents who can expect to have 40% less tooth decay if their water is fluoridated. So is there a down side to water fluoridation?

Numerous large scientific reviews over the last 60 years and ongoing monitoring of all new, relevant scientific studies continue to confirm that water fluoridation is effective and safe - and not linked to any health risks.

The only recognised adverse effect of water fluoridation is the possibility of mild fluorosis which appears as small white lines or white spots on teeth. This is harmless, only of cosmetic interest and usually unnoticeable .  In fact, in most cases, it is something that only a dentist would detect on close examination. Mild fluorosis does not affect the health of the teeth.  It is important to note that while fluorosis is a known possible effect of water fluoridation, the most recent New Zealand Oral Health Survey in 2009 showed that fluorosis in New Zealand was no more common in areas with water fluoridation than those without water fluoridation. More severe fluorosis is known to occur in countries where natural fluoride levels in water are well above the level used for water fluoridation in New Zealand.

Lobby groups that oppose fluoridation often suggest that there is scientific controversy about water fluoridation, however there is overwhelming scientific consensus that water fluoridation works in protecting teeth and that it is safe. As stated by Sir Peter Gluckman, New Zealand's Chief Science Advisor:

"The science of fluoride in water is effectively settled. It has been one of the most thoroughly worked questions in public health science over some decades… The scientific basis for stating that fluoride in water (at the concentrations recommended) is a safe and very effective approach to improving dental health is clear."

One issue that is an important debate about water fluoridation is that some people do not want fluoridated water and so will have less choice if water is fluoridated. This needs to be weighed against the very significant benefits of water fluoridation to everyone in the community and especially to those most at risk of tooth decay who benefit most from it. A decision to not have water fluoridation means that most people will be at more risk of tooth decay and the benefit to children and adolescents of having 40% less tooth decay will be lost. All children and adolescents have a right to the best opportunities society can provide to be healthy and to have good, healthy teeth.  This is a very strong argument in favour of water fluoridation.

Safety and effectiveness

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Sixty years of reputable scientific studies clearly show water fluoridation is safe at the recommended optimal levels. Too much of anything that the body needs, like salt, sunlight or fluoride, can cause harm. There is no risk of getting too much fluoride from drinking fluoridated water.

Some countries, including parts of China, India, Africa and the Middle East, have excessively high levels of naturally occurring fluoride in their drinking water. These high levels (which can be well over 10mg/L) have been found to cause damage to bones (skeletal fluorosis) and teeth when consumed over many years. These problems do not exist in New Zealand.

Fluoride is added to water supplies in accordance to specific quality standards. The Maximum Acceptable Value (MAV) of fluoride in drinking water is set at 1.5mg/L. The amount of fluoride to be added is calculated daily and a weekly water sample is sent for external testing at a Ministry of Health approved laboratory.

Slight white flecking of teeth (known as mild dental fluorosis) has been associated with water fluoridation. This is only a cosmetic issue and would mostly only be noticeable to a dentist. There are also many other causes of flecking or spots on teeth.  The 2009 New Zealand Oral Health Survey reported no significant differences in the levels of dental fluorosis of people living in fluoridated and non-fluoridated areas, and importantly, no cases at all of severe dental fluorosis in the people examined.

For more information about the safety and effectiveness of water fluoridation:

Hear from the experts

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Sir Peter Gluckman the former Prime Minister's Science Advisor talks about the benefits of water fluoridation.


Dr Rudi Johnson, President, Te Ao Mārama - NZ Māori Dental Association perspective on water fluoridation.


Dr John Twaddle - Whakatāne dentist talks about fluoridation.


Warren Lindberg from the Public Health Association speaks on fluoridation.

 For more videos from experts speaking about water fluoridation, visit Fluoride Facts.


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The following websites and links are not specific to New Zealand but contain useful information about water fluoridation, including ethics, safety, effect on the environment and technical information.


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