Community water fluoridation

On this page:

• Community water fluoridation is effective
• Community water fluoridation is safe
• Community water fluoridation is affordable
• Hear from oral health professionals

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Community water fluoridation is effective

Over 60 years of international and New Zealand research shows water fluoridation is both a safe and effective way to reduce tooth decay.

The World Health Organization and other international and national health and scientific experts endorse water fluoridation as the most effective public health measure for preventing dental decay.

Fluoride helps protect teeth by strengthening the tooth surface. Fluoride in drinking water acts like a constant repair kit that neutralises the effect of acids that cause tooth decay and helps to repair damage before it becomes permanent. You can find more information on fluoride’s role in oral health at: Fluoride | Health Information and Services.

Tooth decay can cause pain, inflammation, and infection. If left untreated, it can lead to painful infections, sometimes meaning a tooth needs to be pulled out. Infections from tooth decay can spread further and have the potential to cause significant health harm, including leading to hospitalisation.

In New Zealand, there are ongoing significant differences in the rates of tooth decay between communities that have fluoridated water and communities that do not. This is despite the majority of people across New Zealand using fluoride toothpaste.

New Zealand's most recent national oral health survey shows, on average, 40% less tooth decay was experienced among children living in communities with fluoridated water, compared with children living in communities without fluoridated water.

Community water fluoridation is as an important contributor to health equity. It provides protection from tooth decay for New Zealanders of all ages. It provides the greatest benefits for Māori, Pacific peoples, children, and communities with poorer oral health outcomes.

Community water fluoridation is safe

Review by the Prime Minister’s Chief Science Advisor and the Royal Society of New Zealand Te Apārangi

In 2014, a comprehensive report was published by the Royal Society Te Apārangi, prepared jointly with the Office of the Prime Minister’s Chief Science Advisor, reviewing the substantial body of scientific evidence on the efficacy and safety of fluoridation of public water supplies. The report concluded that:

‘From a medical and public health perspective, water fluoridation at the levels used in New Zealand poses no significant health risks and is effective at reducing the prevalence and severity of tooth decay in communities where it is used. Communities currently without CWF [community water fluoridation] can be confident that this is a safe option that is cost saving and of significant public health benefit – particularly in those communities with high prevalence of dental caries.’

and

‘Our assessment suggests that it is appropriate, from the scientific perspective, that fluoridation be expanded to assist those New Zealand communities that currently do not benefit from this public health measure – particularly those with a high prevalence of dental caries.’

The report from the Prime Minister’s Chief Science Advisor notes that Aotearoa New Zealand adds fluoride to drinking water to reach a level between 0.7 mg and 1 mg per litre and that

‘this range allows the full benefits of fluoride to be achieved while avoiding the adverse impacts that would come with much higher levels of fluoride’

This concentration is considered the optimal level of fluoride in drinking water in New Zealand.

Concerns about water fluoridation

A number of unsubstantiated claims have been made that fluoridation causes or contributes to various health conditions or interferes with natural bodily functions. These claims have not been substantiated by robust studies or epidemiological analyses.

In their 2014 report, the Prime Minister’s Chief Science Advisor and Te Apārangi considered the evidence around health concerns that are commonly raised, and concluded that:

‘the scientific issues raised by those opposed to fluoridation are not supported by the evidence.’

The report also noted that

‘it is important to distinguish between effects of apparent fluoride toxicity at very high intakes, and effects that may occur at the much lower intakes from [community water fluoridation]. Some studies have failed to do so, giving rise to potentially misleading statements and confusion.’

In June 2021, the Office of the Prime Minister’s Chief Science Advisor released an evidence update, confirming that the conclusions of the 2014 report remain appropriate. Both the review and the evidence update can be found on the Office of the Prime Minister’s Chief Science Advisor website.

Dental fluorosis

Dental fluorosis is a condition that causes changes in the appearance of tooth enamel. It can range from very mild where white spots that are barely visible appear on the surface of the teeth to a moderate or severe version where more extensive changes in the enamel, such as pits, occur. Recent evidence from Australia indicates that this fades with time. Tooth development occurs during the first 8 years of life, and beyond this age children are no longer susceptible to fluorosis. 

Dental fluorosis reflects overall fluoride absorption from all sources at a young age and is a known effect of drinking water containing naturally very high concentrations of fluoride. The levels of fluoride used for community water fluoridation in New Zealand are relatively low in the range that is known to cause minimal risk for cosmetically problematic fluorosis. Other factors contribute more significantly to increasing risk, such as young children regularly swallowing fluoridated toothpaste.

No severe form of fluorosis has ever been reported in New Zealand. The 2009 oral health survey indicated that fluorosis prevalence is not increasing, and that levels of fluorosis are similar between fluoridated and non-fluoridated areas.

The Prime Minister’s Chief Science Advisor noted that:

‘One side-effect of fluoride is for a portion of the population it causes minimal white mottling of the enamel...This is very rarely discernible and is definitely not the severe fluorosis that is so often pictured on websites of those opposed to fluoridation of the public water supply.’

Community water fluoridation is affordable

Community water fluoridation is also significantly more cost effective than other public health measures aimed at improving oral health.

Sapere Research Group report

In 2015, the Ministry of Health | Manatū Hauora commissioned the Sapere Research Group to examine the benefits and costs of community water fluoridation.

The Sapere Report reviewed both New Zealand and international evidence. It estimated the benefit of water fluoridation as follows:

• 40% lower lifetime incidence of tooth decay among children and adolescents,
• 48% reduction in hospital admissions for the treatment of tooth decay among children aged 0-4 years,
• 21%reduction in tooth decay among adults aged 18–44 years,
• 30 %reduction in tooth decay among adults aged 45 years and over. 

This independent report concluded:

‘A large body of epidemiological evidence over 60 years, including thorough systematic reviews, confirms water fluoridation prevents and reduces dental decay across the lifespan.’

‘We estimate that adding fluoride to New Zealand’s water treatment plants classified as medium (i.e. those supplying populations over 5,000), is cost-saving; and for those plants classified as minor (i.e. those supplying populations over 500) it is likely to be cost-saving.’

‘Because of the increased amount of dental decay among Māori and those who are most deprived, we expect these groups to have a greater absolute benefit from water fluoridation.’

The Sapere report also estimated the average ongoing cost of community water fluoridation is $2.60 per person per year for water supplies that serve populations of over 500 people and that every dollar spent on water fluoridation will save around $9 in dental care costs. These savings will mostly benefit individual New Zealanders needing to pay for fewer fillings and tooth extractions.

The report estimated that the average cost of fluoridation would be approximately $2.60 per person per year. The average cost of a single filling for an adult would be $250.

Read the full Sapere report together with a further district-level evaluation:

• Review of the Benefits and Costs of Water Fluoridation in New Zealand

Hear from oral health professionals

Hear from trusted New Zealand health professionals about the facts and benefits of this important health measure.

Transcript  

View this video of Dr Riana Clarke, National Clinical Director of Oral Health talking about the value of community water fluoridation. You can watch more fluoridation expert videos on the Ministry of Health's YouTube channel.

Organisations that endorse community water fluoridation