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
20140.798 ppm12120.650 ppm - 0.960 ppm
20150.842 ppm13130.740 ppm - 0.910 ppm
20160.789 ppm12120.680 ppm - 0.870 ppm
20170.763 ppm12120.710 ppm - 0.860 ppm
20180.732 ppm13130.510 ppm - 0.870 ppm
20190.766 ppm12120.670 ppm - 0.880 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
2014-01-081401600030.840 ppm
2014-02-031404100070.850 ppm
2014-03-141407600210.900 ppm
2014-04-011409700030.820 ppm
2014-05-011413200190.960 ppm
2014-06-031416000070.690 ppm
2014-07-081419500280.740 ppm
2014-08-041422300130.700 ppm
2014-09-021425100070.760 ppm
2014-10-14Y1428900600.840 ppm
2014-11-03Y1431100050.830 ppm
2014-12-02Y1434200280.650 ppm
2015-01-05Y1501300190.820 ppm
2015-02-10Y1505000070.880 ppm
2015-03-03Y1506300370.860 ppm
2015-03-11Y1507500260.840 ppm
2015-04-06Y1510300230.870 ppm
2015-05-04Y1512800170.740 ppm
2015-06-04Y1516100050.910 ppm
2015-07-06Y1518900150.870 ppm
2015-08-04Y1521800080.810 ppm
2015-09-08Y1525800330.870 ppm
2015-10-06Y1528500140.870 ppm
2015-11-03Y1531300360.800 ppm
2015-12-15Y1535200150.810 ppm
2016-01-04Y1600800130.850 ppm
2016-02-03Y1604000250.800 ppm
2016-03-16Y1608100330.800 ppm
2016-04-04Y1610400060.840 ppm
2016-05-03Y1613400010.760 ppm
2016-06-06Y1616500090.720 ppm
2016-07-12Y1620000330.720 ppm
2016-08-02Y1621700130.760 ppm
2016-09-08Y1625600220.870 ppm
2016-10-05Y1628800570.680 ppm
2016-11-02Y1630800040.830 ppm
2016-12-05Y1634100060.840 ppm
2017-01-11Y1701200470.780 ppm
2017-02-06Y1704000730.760 ppm
2017-03-08Y1707200360.810 ppm
2017-04-12Y1710700280.730 ppm
2017-05-02Y1712800090.740 ppm
2017-06-08Y1716300530.790 ppm
2017-07-12Y1719800510.710 ppm
2017-08-01Y1721900060.780 ppm
2017-09-05Y1725400250.720 ppm
2017-10-03Y1728200020.740 ppm
2017-11-06Y1731700080.740 ppm
2017-12-04Y1734500010.860 ppm
2018-01-10Y1801800560.610 ppm
2018-02-05Y1803700260.760 ppm
2018-02-20Y1805300810.650 ppm
2018-03-06Y1806600410.770 ppm
2018-04-03Y1809900310.780 ppm
2018-05-02Y1813000410.850 ppm
2018-06-06Y1816200310.700 ppm
2018-07-09Y1819700150.510 ppm
2018-08-07Y1822500250.720 ppm
2018-09-04Y1825300120.770 ppm
2018-10-03Y1828100080.760 ppm
2018-11-06Y1831700310.760 ppm
2018-12-05Y1834400350.870 ppm
2019-01-02Y1900700040.790 ppm
2019-02-04Y1904200090.840 ppm
2019-03-04Y1907000010.820 ppm
2019-04-05Y1909800330.820 ppm
2019-05-06Y1913300030.760 ppm
2019-06-05Y1916100540.760 ppm
2019-07-10Y1919600420.710 ppm
2019-08-05Y1922500130.710 ppm
2019-09-04Y1925400320.700 ppm
2019-10-08Y1928800140.730 ppm
2019-11-13Y1932200210.670 ppm
2019-12-18Y1935400240.880 ppm