EWG's Tap Water Database — 2019 UPDATE



Sunny Slope Water Company

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
20120.910 ppm220.820 ppm - 1.000 ppm
20130.890 ppm110.890 ppm
20140.720 ppm440.670 ppm - 0.790 ppm
20150.685 ppm220.650 ppm - 0.720 ppm
20160.845 ppm220.800 ppm - 0.890 ppm
20170.733 ppm440.590 ppm - 0.900 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
2012-08-153761-004-16301.000 ppm
2012-09-129588-004-09200.820 ppm
2013-04-013761-003-09590.890 ppm
2014-03-039588-006-09050.670 ppm
2014-06-039588-012-09400.690 ppm
2014-08-183761-017-10200.790 ppm
2014-09-169588-003-09250.730 ppm
2015-06-099588-017-10100.650 ppm
2015-09-029588-004-09250.720 ppm
2016-03-073761-003-10180.800 ppm
2016-03-073761-004-10300.890 ppm
2017-03-069588-006-11000.590 ppm
2017-06-309588-012-13100.900 ppm
2017-08-073761-017-11480.720 ppm
2017-09-219588-003-09300.720 ppm