EWG's Tap Water Database — 2019 UPDATE



City of Emporia

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
20120.614 ppm550.580 ppm - 0.690 ppm
20130.564 ppm550.480 ppm - 0.620 ppm
20140.512 ppm550.370 ppm - 0.700 ppm
20150.358 ppm550.150 ppm - 0.420 ppm
20160.360 ppm550.180 ppm - 0.560 ppm
20170.264 ppm53ND - 0.570 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
2012-01-30572967BT0.600 ppm
2012-04-30578202BT0.580 ppm
2012-04-30578189WS0.590 ppm
2012-07-25582471BT0.690 ppm
2012-10-30587312BT0.610 ppm
2013-01-23591682BT0.550 ppm
2013-04-24595102BT0.620 ppm
2013-04-24595101WS0.600 ppm
2013-08-20601876BT0.570 ppm
2013-10-29605114BT0.480 ppm
2014-01-29466410.370 ppm
2014-04-221008110.540 ppm
2014-04-221007800.490 ppm
2014-07-281593580.700 ppm
2014-10-302215680.460 ppm
2015-01-142622150.420 ppm
2015-04-233179160.420 ppm
2015-05-213358280.150 ppm
2015-07-293746360.400 ppm
2015-10-294188160.400 ppm
2016-01-314838850.270 ppm
2016-04-195297740.420 ppm
2016-04-265334420.370 ppm
2016-07-265901470.560 ppm
2016-10-266486630.180 ppm
2017-01-306788820.320 ppm
2017-07-318077610.570 ppm
2017-10-308689120.430 ppm