Key takeaways:
- Water fluoridation remains an effective public health measure, particularly for reducing tooth decay and dental extractions in children.
- Water fluoridation reduces the need for invasive dental treatments, with strong evidence showing fewer hospital extractions in fluoridated areas.
- Historical effectiveness was substantially greater. Before 1975, optimal water fluoridation was associated with the preservation of roughly two additional healthy teeth per person, compared with around one‑quarter of a tooth in more recent decades, indicating that while fluoridation remains beneficial, its impact has diminished over time.
- Its impact on inequalities is mixed: water fluoridation improves oral health across all groups but doesn’t consistently narrow the gap between the most and least deprived.
- Potential harms at UK levels (1 mg/L) appear minimal, with mild dental fluorosis being the main effect; no strong evidence links water fluoridation at these levels to IQ changes or other health conditions.
- Water fluoridation schemes are generally cost‑effective, though the degree of benefit depends on local population characteristics and baseline oral health.
- Overall, the evidence base is moderate in quality and heavily weighted towards studies in children, with far fewer robust studies examining outcomes in adults. Further research is needed, especially on adult outcomes, inequalities, and potential harms at higher water fluoride concentrations.
What is water fluoridation?
Fluoride is a naturally occurring mineral found in water that helps protect teeth from decay. In the UK, around 10% of the population (6.1 million people) receive fluoridated water, either naturally, or where small amounts are added to reach the target concentration of 1 mg/L. This practice aligns with World Health Organisation recommendations (0.5–1.5 mg/L) and is used in many countries worldwide.
Water fluoridation schemes operate across parts of Cumbria, Cheshire, Tyneside, Northumbria, Durham, Humberside, Lincolnshire, Nottinghamshire, Derbyshire, the West Midlands and Bedfordshire, with planned expansion to the North East from 2028. However, fluoridation remains technically challenging in some regions because complex water supply networks can cause fluctuating fluoride levels and periods of suboptimal dosing. This variability should be considered when interpreting evidence and may shape how individuals and dental professionals approach oral health decisions and interventions.
Oral health in the UK has improved significantly in recent decades, with fewer children experiencing tooth decay and fewer adults losing teeth. Much of this improvement is linked to increased fluoride exposure and better dental hygiene. Despite this, tooth decay remains common, affecting 31% of adults and 23.7% of 5-year-olds. Inequalities in dental health also persist, with deprived communities experiencing worse outcomes.
Water fluoridation remains an important public health measure, but one that is often debated. The Academy’s latest independent report summarises the current evidence on the benefits, potential harms and remaining uncertainties of water fluoridation. It is important to note that the quality of evidence is moderate at best, with most studies focusing on children rather than adults.
Benefits of water fluoridation
The evidence shows that water fluoridation at the optimal concentrations (0.7–1.2 mg/L) helps reduce tooth decay, with variance in outcomes across age groups.
- Children: In children, exposure to recommended water fluoride levels is associated with 0.24 (around a quarter of a tooth) fewer decayed, missing or filled primary teeth and 0.27 fewer permanent teeth affected compared with children exposed to low fluoride water.
- Adults: Adults also benefit. Those exposed to recommended water fluoride concentrations show a 2% lower average number of decayed, missing or filled teeth (DMFT) compared with adults receiving lower levels. While this may appear to be a modest difference, at a population level it represents a meaningful reduction in the burden of dental disease. However, there are fewer studies on adults and the evidence quality is moderate at best.
- Reducing invasive treatments: The evidence is particularly strong for the impact of water fluoridation on invasive dental treatment in children. Exposure to recommended or above recommended water fluoride concentrations is linked to a 60% reduction in hospital admissions for decay-related dental extractions compared with children receiving non-fluoridated water. Even low and less-than-recommended concentrations show reductions of 38-44%, though the relationship between dose and effect is less consistent.
Impact on inequalities
The extent to which water fluoridation reduces oral health inequalities is less clear. Among 3-year-olds, the evidence shows no consistent effect across different levels of deprivation. Among 5-year-olds, higher fluoride concentrations reduce tooth decay across all deprivation groups, but this does not necessarily narrow the gap between them. Among 3-year-olds, hildren in the least deprived quintile experience an 86% reduction in the likelihood of dental decay when exposed to the recommended fluoride levels, compared with 36% in the most deprived areas.
In adults, water fluoridation reduces the expected number of invasive dental treatments across all deprivation groups, with the greatest reduction seen in the most deprived groups (0.34 fewer treatments), however effects on the number of missing, decayed or filled teeth remain inconsistent across deprivation groups.
Potential harms
As with any public health intervention, potential harms must be carefully considered. The Cochrane Oral Health group is currently conducting a review (expected Summer 2026) of harms related to water fluoridation, with preliminary findings aligning with our report.
- Dental fluorosis: The most discussed is dental fluorosis, a cosmetic change in the appearance of tooth enamel that occurs during tooth development. The evidence shows that fluorosis becomes more common as water fluoride exposure increases. However, at the concentrations used in the UK, fluorosis is generally mild and not considered harmful.
- Effects of brain development: There is also public concern about the possible effects on brain development. However, evidence suggests that there is no effect on IQ at water fluoride concentrations below 1.2 mg/L. Some studies suggest that concentrations above 1.5 mg/L may be associated with lower IQ, and that this relationship may be dose dependent. However, this evidence base is contested, and further work is underway to understand the effects.
- Other health outcomes: A range of other potential harms have been investigated, including increased risks of Down’s syndrome, kidney stones, hip fractures, and bladder or bone cancer. At concentrations up to 1 mg/L, the evidence suggests no link between fluoridated water and these outcomes. Many of these conditions are more common in older adults‑, and most studies focus on adults rather than children, highlighting the need for continued research.
Cost-effectiveness
In the context of rising living costs and health inequality, the cost effectiveness is another important consideration which drives public opinion. Multiple analyses reveal that water fluoridation schemes are cost-effective or provide net benefits compared with no fluoridation.
It is worth noting that the degree of cost-effectiveness depends on factors such as population size, baseline oral health, and the effect sizes used in economic models. Older studies using larger effect sizes show clearer benefits, while more recent evidence still supports water fluoridation but emphasises the importance of local context.
Public attitudes
Public attitudes also play a role in decisions about fluoridation. Support for adding fluoride to water to prevent tooth decay has remained consistently high across UK regions for more than 15 years. Surveys typically show that around two-thirds of respondents favour fluoridation. For example, an Ipsos MORI survey of 3,516 adults in the West Midlands found that 67% supported adding fluoride to drinking water if it reduced tooth decay, while 22% opposed it. Those who strongly opposed fluoridation often cited a preference for “natural” water, concerns about choice, possible side effects, or taste. Those who were undecided frequently wanted more scientific evidence and clearer information about risks and benefits.
Wider context
The UK Government has identified oral health as a priority in its 2025 10 Year Health Plan for England. The Health and Care Act 2022 transferred responsibility for introducing, varying, or terminating water fluoridation schemes from local authorities to the Secretary of State for Health and Social Care. Currently, no water fluoridation schemes operate in Scotland, Wales or Northern Ireland, and around 6.1 million people in the UK receive fluoridated water, either naturally occurring or added. England’s target concentration of 1 mg/L aligns with the World Health Organisation’s recommended maximum of 1.5 mg/L and is broadly consistent with international practice.
The evidence collected in our report provides an independent, up to date assessment of the benefits, harms, and uncertainties of water fluoridation. While the data shows clear benefits in reducing tooth decay and dental extractions, particularly for children, it also highlights areas where further research is needed, including inequalities, adult outcomes, and potential harms at higher concentrations. As policymakers consider the future of water fluoridation in the UK, this report offers a robust foundation for informed decision-making.
The Academy of Medical Sciences has published a new independent report on water fluoridation, commissioned by Professor Chris Whitty KCB FRS FMedSci, Chief Medical Officer for England. The report brings together contemporary UK and international evidence to support government decision making on the optimal concentration of fluoride in public water supplies.
Read the full report: https://acmedsci.ac.uk/file-download/academy-water-fluoridation-report-2025