EWG's Tap Water Database — 2019 UPDATE



City of Arvada

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
20120.840 ppm220.750 ppm - 0.930 ppm
20130.830 ppm220.810 ppm - 0.850 ppm
20140.675 ppm220.530 ppm - 0.820 ppm
20150.590 ppm660.360 ppm - 0.710 ppm
20160.618 ppm990.110 ppm - 0.840 ppm
20170.609 ppm770.1000 ppm - 0.820 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 Result
2012-02-150.750 ppm
2012-05-140.930 ppm
2013-02-120.810 ppm
2013-06-040.850 ppm
2014-02-120.820 ppm
2014-05-190.530 ppm
2015-02-110.610 ppm
2015-05-120.620 ppm
2015-06-160.710 ppm
2015-08-050.360 ppm
2015-08-050.580 ppm
2015-11-090.660 ppm
2016-02-110.110 ppm
2016-05-140.670 ppm
2016-06-210.240 ppm
2016-08-160.740 ppm
2016-08-160.790 ppm
2016-10-040.730 ppm
2016-10-250.690 ppm
2016-10-250.840 ppm
2016-11-080.750 ppm
2017-02-070.820 ppm
2017-05-160.780 ppm
2017-06-130.580 ppm
2017-08-300.520 ppm
2017-08-300.1000 ppm
2017-10-030.720 ppm
2017-11-070.740 ppm