EWG's Tap Water Database — 2019 UPDATE



City of Manhattan

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
20120.845 ppm440.670 ppm - 1.10 ppm
20130.755 ppm440.680 ppm - 0.800 ppm
20140.782 ppm550.730 ppm - 0.910 ppm
20150.733 ppm440.630 ppm - 0.860 ppm
20160.663 ppm440.540 ppm - 0.730 ppm
20170.658 ppm550.510 ppm - 0.830 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
2012-02-06575082BT1.10 ppm
2012-05-23579305BT0.810 ppm
2012-08-22584375BT0.800 ppm
2012-11-14587933BT0.670 ppm
2013-03-04592869BT0.800 ppm
2013-05-13595971BT0.790 ppm
2013-09-04602549BT0.750 ppm
2013-11-19605771BT0.680 ppm
2014-01-29465340.740 ppm
2014-04-07924160.780 ppm
2014-05-071105840.750 ppm
2014-07-281591280.910 ppm
2014-10-282206790.730 ppm
2015-01-122605400.860 ppm
2015-04-153135820.730 ppm
2015-07-143663760.630 ppm
2015-11-024188700.710 ppm
2016-01-134758840.720 ppm
2016-04-275345830.660 ppm
2016-08-236088020.730 ppm
2016-11-016512280.540 ppm
2017-01-116789460.510 ppm
2017-04-117403270.630 ppm
2017-05-167622640.620 ppm
2017-08-098160140.700 ppm
2017-10-248663310.830 ppm