EWG's Tap Water Database — 2019 UPDATE



Fort Riley

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
20120.690 ppm330.680 ppm - 0.710 ppm
20130.553 ppm440.510 ppm - 0.580 ppm
20140.586 ppm660.500 ppm - 0.750 ppm
20150.681 ppm440.551 ppm - 0.795 ppm
20160.669 ppm440.537 ppm - 0.875 ppm
20170.633 ppm550.390 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
2012-02-15575433BT0.710 ppm
2012-05-22579241BT0.680 ppm
2012-12-11588589BT0.680 ppm
2013-01-23591645BT0.510 ppm
2013-05-01595442BT0.550 ppm
2013-07-22599145BT0.580 ppm
2013-12-10606181BT0.570 ppm
2014-01-2814028040.750 ppm
2014-01-28459580.540 ppm
2014-04-2214112010.572 ppm
2014-05-051090900.500 ppm
2014-07-0114182010.572 ppm
2014-10-0114274140.579 ppm
2015-01-0715007050.697 ppm
2015-04-0215092050.551 ppm
2015-07-0115182010.680 ppm
2015-10-0515278010.795 ppm
2016-01-1316013110.875 ppm
2016-04-1916110120.642 ppm
2016-07-0516187010.537 ppm
2016-10-1216286010.623 ppm
2017-01-0517004070.678 ppm
2017-04-0317093010.642 ppm
2017-06-017695340.390 ppm
2017-07-1917201010.626 ppm
2017-10-0217275010.830 ppm