EWG's Tap Water Database



Freedom District

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
20100.923 ppm440.870 ppm - 1.000 ppm
20110.447 ppm32ND - 0.680 ppm
20120.710 ppm440.610 ppm - 0.890 ppm
20130.575 ppm440.300 ppm - 0.700 ppm
20140.688 ppm440.600 ppm - 0.760 ppm
20150.630 ppm550.580 ppm - 0.700 ppm

ppm = parts per million.

State and national drinking water standards and health guidelines

EPA Maximum Contaminant
Level (MCL) 4 ppm

The enforceable federal standard that defines the highest level of a contaminant allowed in drinking water.

ppm = parts per million.

EPA Maximum Contaminant
Level Goal (MCLG)4 ppm

A non-enforceable federal health guideline. For cancer-causing chemicals, these health goals are typically set to zero.

ppm = parts per million.

All test results

Date Lab ID Result
2010-01-04100104_01_825263000.870 ppm
2010-04-05100405_01_838308000.880 ppm
2010-07-12100712_01_854393000.940 ppm
2010-10-26101026_01_872971001.000 ppm
2011-01-03110103_01_988310200.680 ppm
2011-04-04110404_01_989790800.660 ppm
2012-01-03120103_01_994511500.620 ppm
2012-07-02120702_01_997562500.720 ppm
2012-10-01121001_01_999131400.890 ppm
2012-10-01121001_02_999104900.610 ppm
2013-01-03130103_01_005817000.620 ppm
2013-04-04130404_01_020210000.300 ppm
2013-07-08130708_01_1035643-0.700 ppm
2013-10-14131014_01_1053206-0.680 ppm
2014-04-10140410_01_2001127-0.600 ppm
2014-05-05140505_01_2004896-0.760 ppm
2014-08-06140806_02_000531000.730 ppm
2014-08-06140806_01_000531000.660 ppm
2015-01-05150105_01_2047745-0.650 ppm
2015-04-0620633410010.700 ppm
2015-12-2121148690010.620 ppm
2015-12-2121148700010.580 ppm
2015-12-2821156030010.600 ppm