Fluoride
Lake Mills Waterworks
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
Samples exceeding legal limit (MCL)
Samples exceeding
health guidelines
Testing results - average by year
| Year | Average result | Samples taken | Detections | Range of results |
|---|---|---|---|---|
| 2014 | 0.843 ppm | 27 | 27 | 0.0990 ppm - 1.20 ppm |
| 2015 | 0.767 ppm | 24 | 24 | 0.400 ppm - 1.20 ppm |
| 2016 | 0.682 ppm | 24 | 24 | 0.340 ppm - 0.840 ppm |
| 2017 | 0.674 ppm | 27 | 27 | 0.250 ppm - 0.950 ppm |
| 2018 | 0.857 ppm | 24 | 24 | 0.700 ppm - 1.03 ppm |
| 2019 | 0.833 ppm | 24 | 24 | 0.710 ppm - 1.000 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 |
|---|---|---|
| 2014-01-08 | 115314001 | 1.18 ppm |
| 2014-01-08 | 115314001 | 1.20 ppm |
| 2014-02-24 | 120606001 | 1.10 ppm |
| 2014-02-24 | 120606001 | 1.20 ppm |
| 2014-03-19 | 124079001 | 1.10 ppm |
| 2014-03-19 | 124079001 | 1.20 ppm |
| 2014-04-08 | 126644001 | 0.899 ppm |
| 2014-04-08 | 126644001 | 1.07 ppm |
| 2014-05-06 | 130695001 | 1.04 ppm |
| 2014-05-06 | 130695001 | 1.13 ppm |
| 2014-06-10 | 796035 | 0.0990 ppm |
| 2014-06-10 | 796034 | 0.120 ppm |
| 2014-06-10 | 796033 | 0.120 ppm |
| 2014-06-23 | 140571001 | 0.900 ppm |
| 2014-06-23 | 140571001 | 0.960 ppm |
| 2014-07-22 | 146664001 | 1.08 ppm |
| 2014-07-22 | 146664001 | 1.17 ppm |
| 2014-08-20 | 152516001 | 0.860 ppm |
| 2014-08-20 | 152516001 | 0.862 ppm |
| 2014-09-16 | 157479001 | 0.596 ppm |
| 2014-09-16 | 157479001 | 0.600 ppm |
| 2014-10-20 | 164328001 | 0.695 ppm |
| 2014-10-20 | 164328001 | 0.730 ppm |
| 2014-11-11 | 167797001 | 0.640 ppm |
| 2014-11-11 | 167797001 | 0.651 ppm |
| 2014-12-08 | 171339001 | 0.770 ppm |
| 2014-12-08 | 171339001 | 0.795 ppm |
| 2015-01-06 | 174459001 | 0.649 ppm |
| 2015-01-06 | 174459001 | 0.700 ppm |
| 2015-02-17 | 179807001 | 1.01 ppm |
| 2015-02-17 | 179807001 | 1.01 ppm |
| 2015-03-17 | 183800001 | 0.999 ppm |
| 2015-03-17 | 183800001 | 1.01 ppm |
| 2015-04-20 | 188531001 | 0.788 ppm |
| 2015-04-20 | 188531001 | 0.800 ppm |
| 2015-05-18 | 193851001 | 0.783 ppm |
| 2015-05-18 | 193851001 | 0.830 ppm |
| 2015-06-15 | 199452001 | 0.678 ppm |
| 2015-06-15 | 199452001 | 0.770 ppm |
| 2015-07-21 | 206915001 | 0.672 ppm |
| 2015-07-21 | 206915001 | 0.770 ppm |
| 2015-08-18 | 212325001 | 0.740 ppm |
| 2015-08-18 | 212325001 | 1.20 ppm |
| 2015-09-21 | 218563001 | 0.680 ppm |
| 2015-09-21 | 218563001 | 0.682 ppm |
| 2015-10-13 | 223294001 | 0.400 ppm |
| 2015-10-13 | 223294001 | 0.684 ppm |
| 2015-11-17 | 228907001 | 0.678 ppm |
| 2015-11-17 | 228907001 | 0.730 ppm |
| 2015-12-15 | 232748001 | 0.490 ppm |
| 2015-12-15 | 232748001 | 0.659 ppm |
| 2016-01-19 | 236122001 | 0.570 ppm |
| 2016-01-19 | 236122001 | 0.664 ppm |
| 2016-02-17 | 240128001 | 0.690 ppm |
| 2016-02-17 | 240128001 | 0.761 ppm |
| 2016-03-14 | 243660001 | 0.704 ppm |
| 2016-03-14 | 243660001 | 0.840 ppm |
| 2016-04-20 | 249771001 | 0.689 ppm |
| 2016-04-20 | 249771001 | 0.780 ppm |
| 2016-05-23 | 255863001 | 0.627 ppm |
| 2016-05-23 | 255863001 | 0.650 ppm |
| 2016-06-22 | 262030001 | 0.430 ppm |
| 2016-06-22 | 262030001 | 0.650 ppm |
| 2016-07-19 | 266995001 | 0.738 ppm |
| 2016-07-19 | 266995001 | 0.760 ppm |
| 2016-08-17 | 272666001 | 0.657 ppm |
| 2016-08-17 | 272666001 | 0.690 ppm |
| 2016-09-21 | 279308001 | 0.751 ppm |
| 2016-09-21 | 279308001 | 0.790 ppm |
| 2016-10-17 | 284083001 | 0.707 ppm |
| 2016-10-17 | 284083001 | 0.740 ppm |
| 2016-11-21 | 289845001 | 0.690 ppm |
| 2016-11-21 | 289845001 | 0.815 ppm |
| 2016-12-12 | 292336001 | 0.340 ppm |
| 2016-12-12 | 292336001 | 0.646 ppm |
| 2017-01-23 | 297015001 | 0.250 ppm |
| 2017-01-23 | 297015001 | 0.300 ppm |
| 2017-02-22 | 301192001 | 0.560 ppm |
| 2017-02-22 | 301192001 | 0.569 ppm |
| 2017-03-01 | 975573 | 0.520 ppm |
| 2017-03-08 | 976725 | 0.720 ppm |
| 2017-03-08 | 976728 | 0.820 ppm |
| 2017-03-14 | 303948001 | 0.700 ppm |
| 2017-03-14 | 303948001 | 0.709 ppm |
| 2017-04-19 | 310793001 | 0.779 ppm |
| 2017-04-19 | 310793001 | 0.930 ppm |
| 2017-05-10 | 315025001 | 0.778 ppm |
| 2017-05-10 | 315025001 | 0.950 ppm |
| 2017-06-20 | 322970001 | 0.420 ppm |
| 2017-06-20 | 322970001 | 0.764 ppm |
| 2017-07-18 | 329102001 | 0.690 ppm |
| 2017-07-18 | 329102001 | 0.748 ppm |
| 2017-08-21 | 336924001 | 0.490 ppm |
| 2017-08-21 | 336924001 | 0.761 ppm |
| 2017-09-18 | 342630001 | 0.420 ppm |
| 2017-09-18 | 342630001 | 0.718 ppm |
| 2017-10-18 | 349770001 | 0.610 ppm |
| 2017-10-18 | 349770001 | 0.838 ppm |
| 2017-11-20 | 355320001 | 0.750 ppm |
| 2017-11-20 | 355320001 | 0.823 ppm |
| 2017-12-11 | 358410001 | 0.740 ppm |
| 2017-12-11 | 358410001 | 0.832 ppm |
| 2018-01-23 | 363901001 | 0.810 ppm |
| 2018-01-23 | 363901001 | 0.842 ppm |
| 2018-02-20 | 367597001 | 0.760 ppm |
| 2018-02-20 | 367597001 | 0.837 ppm |
| 2018-03-19 | 371643001 | 0.730 ppm |
| 2018-03-19 | 371643001 | 0.816 ppm |
| 2018-04-17 | 376578001 | 0.861 ppm |
| 2018-04-17 | 376578001 | 1.03 ppm |
| 2018-05-09 | 381024001 | 0.750 ppm |
| 2018-05-09 | 381024001 | 0.827 ppm |
| 2018-06-19 | 389436001 | 0.841 ppm |
| 2018-06-19 | 389436001 | 1.000 ppm |
| 2018-07-23 | 396008001 | 0.770 ppm |
| 2018-07-23 | 396008001 | 0.936 ppm |
| 2018-08-27 | 403339001 | 0.830 ppm |
| 2018-08-27 | 403339001 | 0.928 ppm |
| 2018-09-11 | 406627001 | 0.900 ppm |
| 2018-09-11 | 406627001 | 0.926 ppm |
| 2018-10-16 | 414661001 | 0.700 ppm |
| 2018-10-16 | 414661001 | 0.956 ppm |
| 2018-11-07 | 418573001 | 0.710 ppm |
| 2018-11-07 | 418573001 | 0.928 ppm |
| 2018-12-11 | 423617001 | 0.910 ppm |
| 2018-12-11 | 423617001 | 0.973 ppm |
| 2019-01-22 | 428610001 | 0.710 ppm |
| 2019-01-22 | 428610001 | 0.778 ppm |
| 2019-02-21 | 432538001 | 0.764 ppm |
| 2019-02-21 | 432538001 | 1.000 ppm |
| 2019-03-20 | 436353001 | 0.770 ppm |
| 2019-03-20 | 436353001 | 0.900 ppm |
| 2019-04-22 | 441510001 | 0.710 ppm |
| 2019-04-22 | 441510001 | 0.753 ppm |
| 2019-05-07 | 444359001 | 0.775 ppm |
| 2019-05-07 | 444359001 | 0.950 ppm |
| 2019-06-25 | 453775001 | 0.891 ppm |
| 2019-06-25 | 453775001 | 1.000 ppm |
| 2019-07-22 | 458754001 | 0.786 ppm |
| 2019-07-22 | 458754001 | 0.910 ppm |
| 2019-08-19 | 464365001 | 0.803 ppm |
| 2019-08-19 | 464365001 | 1.000 ppm |
| 2019-09-17 | 470553001 | 0.743 ppm |
| 2019-09-17 | 470553001 | 0.820 ppm |
| 2019-10-21 | 477248001 | 0.743 ppm |
| 2019-10-21 | 477248001 | 0.900 ppm |
| 2019-11-19 | 482222001 | 0.821 ppm |
| 2019-11-19 | 482222001 | 0.900 ppm |
| 2019-12-10 | 485301001 | 0.780 ppm |
| 2019-12-10 | 485301001 | 0.788 ppm |