Water fluoridation
December 2025
4 minutes
Optimal concentration of water fluoridation in the UK: evidence synthesis report
At a glance
Commissioned by the Chief Medical Officer for England, this report brings together current evidence on adding fluoride to drinking water to inform UK policy on the optimal concentration. It concludes that water fluoridation at current target levels benefits dental health, while highlighting important uncertainties, trade-offs and the need to consider local context when decisions are made.
Date published: December 2025
Summary
The Chief Medical Officer for England requested that the Academy of Medical Sciences synthesise the evidence on the optimal level of fluoride in drinking water to support government policy. Drawing on evidence from the UK and internationally, the report examines the benefits, potential harms and remaining uncertainties associated with water fluoridation.
The review finds that water fluoridation at the current optimal level (0.7–1.2 mg/L) reduces tooth decay in both children and adults. In children, it is associated with fewer hospital admissions for tooth extractions caused by decay, while in adults it is linked to fewer invasive dental treatments such as fillings and extractions.
Evidence on reducing oral health inequalities is less clear. Findings in children vary by age and deprivation level, while evidence in adults is mixed, although some studies suggest the greatest reductions in invasive dental treatments may occur in the most deprived groups.
The report also considers potential harms. Higher fluoride levels are associated with an increased risk of dental fluorosis, which at these concentrations is usually mild and cosmetic. At water fluoride levels below 1.2 mg/L, the review found no evidence of an effect on neurodevelopment or cognition, as measured by IQ, and no evidence of links with Down’s syndrome, kidney stones, hip fractures, or bladder or bone cancer at concentrations up to 1 mg/L.
Looking beyond health outcomes, the report concludes that water fluoridation is generally cost-effective or provides an overall net benefit, although this depends on local population characteristics and oral health need. Public support for fluoridation has remained consistently high across the UK over the past 15 years.
Overall, the evidence supports water fluoridation at the current target level in England as beneficial for dental health, while recognising that much of the evidence comes from observational studies and should be considered alongside wider improvements in oral health, including fluoride toothpaste and changes in dental habits.
Why this matters
Oral health is a key part of the Academy’s wider work on prevention, public health and reducing health inequalities. It affects people throughout their lives, reflects broader social and economic inequalities, and demonstrates how population-level interventions can improve health outcomes.
This evidence synthesis was commissioned to inform a live government policy question at a time when oral health has been identified as a priority in the UK Government’s 10 Year Health Plan for England. It also comes as the water fluoridation programme is set to expand across the North East of England from 2028.
By bringing together the best available evidence on the benefits, risks and uncertainties of water fluoridation, the report supports evidence-informed decision-making on an important public health intervention. It complements the Academy’s wider work on prevention, early childhood, child health and tackling health inequalities, highlighting the role that population-level policies can play in improving health outcomes across society.
Explore related work
- Explore our wider work on prevention and public health policy.
- Read related work on early childhood, prevention and health inequalities.
- Learn more about our policy work on evidence-informed decision-making.
Work with us
We welcome opportunities to undertake commissioned evidence synthesis and analysis that bring together independent expertise to inform policy and practice. We are particularly interested in working with policymakers, public bodies, funders and others on live questions where rigorous, evidence-informed analysis can support better decision-making.
About this report
This report was developed with oversight from a steering group of experts from across the Academy’s Fellowship and beyond.