EWG's Tap Water Database — 2021 UPDATE




Fluoride occurs naturally in surface and groundwater and is also added to drinking water by many water systems. Read More.

Fluoride has been promoted as a chemical that reduces dental cavities. Yet it is now well-established that fluoride primarily exerts its protective effects through topical mechanisms, such as sodium fluoride in toothpaste and mouthwash. In contrast, long-term ingestion of fluoride in water increases dental fluorosis, which includes mottling, pitting and weakening of the teeth. EPA's maximum legal limit is set at 4 parts per million (ppm) to prevent skeletal fluorosis, a condition where bones become brittle and more susceptible to fractures, although these effects may occur at lower doses.

Even fluoride levels of 0.7 ppm, the amount of fluoride in drinking water recommended by the U.S. Public Health Service, can result in too much fluoride for bottle-fed babies. EWG recommends that caregivers mix baby formula with fluoride-free water. The National Toxicology Program is investigating the potential for low doses of fluoride to alter thyroid function and childhood brain development.





Samples exceeding legal limit (MCL)


Samples exceeding
health guidelines

Testing results - average by year

YearAverage resultSamples takenDetectionsRange of results
20150.690 ppm109ND - 1.20 ppm
20180.670 ppm10100.390 ppm - 0.970 ppm

ppm = parts per million

State and national drinking water standards and health guidelines

EPA Maximum Contaminant
Level (MCL) 4 ppm

ppm = parts per million

All test results

Date Lab ID Result
2015-07-0900281-REI CONSUL1.10 ppm
2015-07-0900281-REI CONSUL0.900 ppm
2015-07-0900281-REI CONSUL0.800 ppm
2015-07-0900281-REI CONSUL0.800 ppm
2015-07-0900281-REI CONSUL0.800 ppm
2015-07-0900281-REI CONSUL0.600 ppm
2015-07-0900281-REI CONSUL0.500 ppm
2015-07-0900281-REI CONSUL0.200 ppm
2015-07-0900281-REI CONSULND
2015-07-0900281-REI CONSUL1.20 ppm
2018-07-0218070141-19A0.720 ppm
2018-07-0218070141-17A0.540 ppm
2018-07-0218070141-15A0.850 ppm
2018-07-0218070141-13A0.390 ppm
2018-07-0218070141-11A0.440 ppm
2018-07-0218070141-09A0.760 ppm
2018-07-0218070141-07A0.970 ppm
2018-07-0218070141-05A0.870 ppm
2018-07-0218070141-03A0.620 ppm
2018-07-0218070141-01A0.540 ppm