EWG's Tap Water Database — 2019 UPDATE



Pella Water Works Department

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
20120.726 ppm12120.620 ppm - 0.840 ppm
20130.711 ppm13130.640 ppm - 0.800 ppm
20140.701 ppm12120.610 ppm - 0.790 ppm
20150.693 ppm12120.640 ppm - 0.790 ppm
20170.730 ppm110.730 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
2012-01-1818820570.780 ppm
2012-02-1518872510.730 ppm
2012-03-1418925150.670 ppm
2012-04-2518987300.650 ppm
2012-05-2319036100.750 ppm
2012-06-0619086000.700 ppm
2012-07-1819175840.840 ppm
2012-08-1519242760.720 ppm
2012-09-2619311890.690 ppm
2012-10-1219382050.760 ppm
2012-11-2119446430.620 ppm
2012-12-1919503050.800 ppm
2013-01-1619565630.640 ppm
2013-02-1319628860.800 ppm
2013-02-2719613160.650 ppm
2013-03-1319672900.750 ppm
2013-04-1019732260.690 ppm
2013-05-2219781030.640 ppm
2013-06-1919846500.700 ppm
2013-07-1719908730.750 ppm
2013-08-1419995700.730 ppm
2013-09-1120041150.760 ppm
2013-10-0920115580.760 ppm
2013-11-2020188580.680 ppm
2013-12-1820240260.690 ppm
2014-01-1520295230.760 ppm
2014-02-1220349610.720 ppm
2014-03-2620404200.750 ppm
2014-04-0920462310.710 ppm
2014-05-2120525720.650 ppm
2014-06-0420579310.610 ppm
2014-07-2320634680.720 ppm
2014-08-2020726680.680 ppm
2014-09-1720790930.630 ppm
2014-10-2920868250.730 ppm
2014-11-1220905680.790 ppm
2014-12-1020973190.660 ppm
2015-01-0718D010715RT0.680 ppm
2015-02-1818D021815RT0.790 ppm
2015-03-1818D031815RT0.640 ppm
2015-04-1518D041515RT0.690 ppm
2015-05-2718D052715RT0.680 ppm
2015-06-1018D061015RT0.700 ppm
2015-07-2218D072215RT0.680 ppm
2015-08-0518D080515RT0.740 ppm
2015-09-0218D090215RT0.700 ppm
2015-10-1418D101415RT0.700 ppm
2015-11-1118D111115RT0.670 ppm
2015-12-0918D120915RT0.640 ppm
2017-12-2718D122717RT0.730 ppm