What Is the Level of Fluoride in UK Water?
Updated: Sep 19, 2025
Last reviewed: September 2026
Quick answer The legal maximum for fluoride in UK drinking water is 1.5 milligrams per litre (1.5 mg/l, the same as 1.5 ppm). Most water has a little fluoride naturally, and some areas of England are fluoridated to about 1 mg/l to help prevent tooth decay. Your water company can tell you your level, and a strip test shows it at your own tap.
Want your area’s level? The Fluoride Checker shows the DWI’s typical fluoride level for your postcode in England and Wales.
The UK standard for fluoride
“The maximum permitted value of fluoride in drinking water is 1.5mg/l (milligrams per litre).” (DWI) “Fluoride occurs naturally in some water sources and enforcement relates to these situations as well as to artificial fluoridation schemes.” (DWI)
“If the standard of 1.5mg/l is breached, then the Drinking Water Inspectorate has the power to take enforcement action to require the water company to rectify the breach.” (DWI)
Natural fluoride and fluoridation
“Fluoride is naturally present at low levels in most drinking water in England and Wales.” (DWI)
“Fluoridation is the term used to describe the dosing of water supplies to bring the fluoride level up to 1 milligram per litre as a public health measure intended to prevent tooth decay.” (DWI) “In England, about one in ten people have fluoridated water.” (Oral Health Foundation)
Who decides
“In England, the decision to fluoridate your water supply is made by the Secretary of State.” (DWI)
“When deciding whether to fluoridate the Secretary of State must carry out a consultation exercise, the findings of which must be taken into consideration when reaching a final decision.” (DWI)
“In Wales, health decisions about fluoridation are taken by the Welsh Government.” (DWI)
“The law only permits a water company to fluoridate under a contract with the Department of Health and Social Care.” (DWI)
Fluoride and teeth
“Fluoride is a natural mineral. It is found in things like tea, fish, and some water supplies.” (Oral Health Foundation) It is “also added to many dental products.” (Oral Health Foundation)
“Fluoride has been used for many years to help protect teeth.” (Oral Health Foundation) “Fluoride is safe and very effective when used in the right amount.” (Oral Health Foundation)
The amount matters while teeth are forming: “Too much fluoride while teeth are forming can cause dental fluorosis.” (Oral Health Foundation) “This can lead to faint white marks on the teeth.” (Oral Health Foundation) “It is usually mild and does not affect how teeth work.” (Oral Health Foundation)
Making up drinks or formula for a baby? Read Can babies drink tap water?.
How to find your fluoride level
Ask your water company. “You can obtain a free copy of the water quality test results for the water supply to your home or workplace by contacting your local water company.” (DWI)
Check your area. The Fluoride Checker uses the DWI’s “typical concentrations of fluoride in drinking water supplies across England and Wales” (DWI) for your postcode.
Test your own tap. Fluoride strips read in ppm (1 ppm is the same as 1 mg/l). Test the cold kitchen tap, and compare a filter or bottled water if you use one. See the Fluoride Test Kit.
On a private supply? No water company holds results for you, and fluoride occurs naturally in some sources, so a test is the only way to know.
Frequently asked questions
What is the maximum fluoride level in UK water?
1.5 mg/l. “The maximum permitted value of fluoride in drinking water is 1.5mg/l (milligrams per litre).” (DWI)
Is my water fluoridated?
“In England, about one in ten people have fluoridated water.” (Oral Health Foundation) Ask your water company, or check your postcode with the Fluoride Checker.
Does fluoride occur naturally in water?
Yes. “Fluoride is naturally present at low levels in most drinking water in England and Wales.” (DWI)
How do I test fluoride at home?
Use fluoride strips at the cold kitchen tap. A home screen is a first check, not a lab result.
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