EWG's Tap Water Database — 2019 UPDATE



Miramar (East & West) Plants

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
20120.526 ppm440.147 ppm - 1.03 ppm
20130.861 ppm220.819 ppm - 0.903 ppm
20140.833 ppm220.810 ppm - 0.855 ppm
20150.721 ppm440.697 ppm - 0.745 ppm
20160.701 ppm440.653 ppm - 0.748 ppm
20170.808 ppm440.717 ppm - 0.898 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 Result
2012-08-030.742 ppm
2012-08-031.03 ppm
2012-09-130.183 ppm
2012-09-130.147 ppm
2013-09-100.903 ppm
2013-09-100.819 ppm
2014-09-090.810 ppm
2014-09-090.855 ppm
2015-09-090.697 ppm
2015-09-090.745 ppm
2015-09-090.697 ppm
2015-09-100.745 ppm
2016-09-130.653 ppm
2016-09-130.748 ppm
2016-09-130.748 ppm
2016-09-130.653 ppm
2017-09-290.717 ppm
2017-09-290.898 ppm
2017-09-290.898 ppm
2017-09-290.717 ppm