What it is
Fluoride is a naturally occurring mineral. Some public supplies have it added at low levels for dental health; in private supplies it comes from the ground.
Where it comes from
Fluoride dissolves from fluoride-bearing rocks, so levels depend on local geology. Most UK groundwaters are well below the guideline; a few areas have naturally high levels.
Why it matters
At low levels fluoride reduces tooth decay. Above the guideline, long-term intake can mottle children's teeth, and at much higher levels affect bones. The guideline is set to keep lifetime intake within the safe range.
What can be done about it
Fluoride is not removed by ordinary filters or softeners. Reverse osmosis at the kitchen tap, or activated alumina filtration, is used where a reduction is needed.
Information last reviewed 5 October 2026 by Pozzani Pure Water.