Fluoride
Horicon 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 | 0.748 ppm | 27 | 27 | 0.430 ppm - 1.07 ppm |
| 2015 | 0.746 ppm | 24 | 24 | 0.670 ppm - 0.850 ppm |
| 2016 | 0.723 ppm | 24 | 24 | 0.670 ppm - 0.838 ppm |
| 2017 | 0.706 ppm | 27 | 27 | 0.410 ppm - 0.780 ppm |
| 2018 | 0.781 ppm | 24 | 24 | 0.690 ppm - 0.850 ppm |
| 2019 | 0.751 ppm | 24 | 24 | 0.690 ppm - 0.837 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 |
|---|---|---|
| 2014-01-15 | 116417001 | 0.730 ppm |
| 2014-01-15 | 116417001 | 0.777 ppm |
| 2014-02-25 | 121145001 | 0.740 ppm |
| 2014-02-25 | 121145001 | 0.754 ppm |
| 2014-03-10 | 122447001 | 0.698 ppm |
| 2014-03-10 | 122447001 | 0.720 ppm |
| 2014-04-08 | 126963001 | 0.724 ppm |
| 2014-04-08 | 126963001 | 0.810 ppm |
| 2014-05-07 | 131224001 | 0.804 ppm |
| 2014-05-07 | 131224001 | 0.810 ppm |
| 2014-06-04 | 4060167-03 | 0.430 ppm |
| 2014-06-04 | 4060167-01 | 0.540 ppm |
| 2014-06-04 | 4060167-02 | 1.07 ppm |
| 2014-06-10 | 138425001 | 0.709 ppm |
| 2014-06-10 | 138425001 | 0.720 ppm |
| 2014-07-07 | 143569001 | 0.789 ppm |
| 2014-07-07 | 143569001 | 0.790 ppm |
| 2014-08-18 | 151840001 | 0.710 ppm |
| 2014-08-18 | 151840001 | 0.724 ppm |
| 2014-09-02 | 154878001 | 0.700 ppm |
| 2014-09-02 | 154878001 | 0.722 ppm |
| 2014-10-22 | 165270001 | 0.718 ppm |
| 2014-10-22 | 165270001 | 0.760 ppm |
| 2014-11-12 | 168231001 | 0.730 ppm |
| 2014-11-12 | 168231001 | 0.770 ppm |
| 2014-12-03 | 171103001 | 0.841 ppm |
| 2014-12-03 | 171103001 | 0.900 ppm |
| 2015-01-21 | 176738001 | 0.670 ppm |
| 2015-01-21 | 176738001 | 0.687 ppm |
| 2015-02-18 | 180319001 | 0.691 ppm |
| 2015-02-18 | 180319001 | 0.770 ppm |
| 2015-03-16 | 183831001 | 0.711 ppm |
| 2015-03-16 | 183831001 | 0.850 ppm |
| 2015-04-21 | 189297001 | 0.686 ppm |
| 2015-04-21 | 189297001 | 0.800 ppm |
| 2015-05-07 | 193231001 | 0.756 ppm |
| 2015-05-07 | 193231001 | 0.760 ppm |
| 2015-06-09 | 199109001 | 0.690 ppm |
| 2015-06-09 | 199109001 | 0.745 ppm |
| 2015-07-08 | 204513001 | 0.670 ppm |
| 2015-07-08 | 204513001 | 0.694 ppm |
| 2015-08-11 | 211516001 | 0.820 ppm |
| 2015-08-11 | 211516001 | 0.843 ppm |
| 2015-09-08 | 216426001 | 0.673 ppm |
| 2015-09-08 | 216426001 | 0.700 ppm |
| 2015-10-21 | 225173001 | 0.794 ppm |
| 2015-10-21 | 225173001 | 0.800 ppm |
| 2015-11-09 | 228048001 | 0.740 ppm |
| 2015-11-09 | 228048001 | 0.754 ppm |
| 2015-12-16 | 233191001 | 0.790 ppm |
| 2015-12-16 | 233191001 | 0.819 ppm |
| 2016-01-20 | 236578001 | 0.670 ppm |
| 2016-01-20 | 236578001 | 0.672 ppm |
| 2016-02-01 | 239483001 | 0.670 ppm |
| 2016-02-01 | 239483001 | 0.682 ppm |
| 2016-03-17 | 245402001 | 0.690 ppm |
| 2016-03-17 | 245402001 | 0.706 ppm |
| 2016-04-11 | 248784001 | 0.820 ppm |
| 2016-04-11 | 248784001 | 0.838 ppm |
| 2016-05-24 | 256796001 | 0.756 ppm |
| 2016-05-24 | 256796001 | 0.780 ppm |
| 2016-06-20 | 262301001 | 0.728 ppm |
| 2016-06-20 | 262301001 | 0.730 ppm |
| 2016-07-18 | 267567001 | 0.710 ppm |
| 2016-07-18 | 267567001 | 0.728 ppm |
| 2016-08-19 | 274169001 | 0.720 ppm |
| 2016-08-19 | 274169001 | 0.722 ppm |
| 2016-09-19 | 279635001 | 0.734 ppm |
| 2016-09-19 | 279635001 | 0.740 ppm |
| 2016-10-18 | 285486001 | 0.710 ppm |
| 2016-10-18 | 285486001 | 0.730 ppm |
| 2016-11-02 | 288464001 | 0.710 ppm |
| 2016-11-02 | 288464001 | 0.725 ppm |
| 2016-12-20 | 293930001 | 0.678 ppm |
| 2016-12-20 | 293930001 | 0.710 ppm |
| 2017-01-24 | 297676001 | 0.720 ppm |
| 2017-01-24 | 297676001 | 0.734 ppm |
| 2017-02-20 | 301255001 | 0.719 ppm |
| 2017-02-20 | 301255001 | 0.720 ppm |
| 2017-03-17 | 305717001 | 0.740 ppm |
| 2017-03-17 | 305717001 | 0.743 ppm |
| 2017-04-03 | 309671001 | 0.750 ppm |
| 2017-04-03 | 309671001 | 0.758 ppm |
| 2017-05-17 | 317470001 | 0.750 ppm |
| 2017-05-17 | 317470001 | 0.752 ppm |
| 2017-06-17 | 323462001 | 0.750 ppm |
| 2017-06-17 | 323462001 | 0.780 ppm |
| 2017-07-18 | 329918001 | 0.730 ppm |
| 2017-07-18 | 329918001 | 0.736 ppm |
| 2017-08-01 | 17H0098-01 | 0.410 ppm |
| 2017-08-01 | 17H0101-01 | 0.440 ppm |
| 2017-08-01 | 17H0093-01 | 0.490 ppm |
| 2017-08-17 | 338428001 | 0.730 ppm |
| 2017-08-17 | 338428001 | 0.775 ppm |
| 2017-09-22 | 344896001 | 0.710 ppm |
| 2017-09-22 | 344896001 | 0.737 ppm |
| 2017-10-06 | 348360001 | 0.740 ppm |
| 2017-10-06 | 348360001 | 0.774 ppm |
| 2017-11-08 | 353520001 | 0.700 ppm |
| 2017-11-08 | 353520001 | 0.708 ppm |
| 2017-12-13 | 359279001 | 0.720 ppm |
| 2017-12-13 | 359279001 | 0.736 ppm |
| 2018-01-16 | 364074001 | 0.750 ppm |
| 2018-01-16 | 364074001 | 0.764 ppm |
| 2018-02-16 | 367905001 | 0.849 ppm |
| 2018-02-16 | 367905001 | 0.850 ppm |
| 2018-03-09 | 371410001 | 0.800 ppm |
| 2018-03-09 | 371410001 | 0.826 ppm |
| 2018-04-02 | 375831001 | 0.789 ppm |
| 2018-04-02 | 375831001 | 0.790 ppm |
| 2018-05-23 | 385201001 | 0.690 ppm |
| 2018-05-23 | 385201001 | 0.721 ppm |
| 2018-06-04 | 388541001 | 0.720 ppm |
| 2018-06-04 | 388541001 | 0.730 ppm |
| 2018-07-20 | 396854001 | 0.750 ppm |
| 2018-07-20 | 396854001 | 0.766 ppm |
| 2018-08-03 | 399880001 | 0.760 ppm |
| 2018-08-03 | 399880001 | 0.777 ppm |
| 2018-09-15 | 408925001 | 0.790 ppm |
| 2018-09-15 | 408925001 | 0.827 ppm |
| 2018-10-17 | 416178001 | 0.770 ppm |
| 2018-10-17 | 416178001 | 0.823 ppm |
| 2018-11-01 | 418597001 | 0.772 ppm |
| 2018-11-01 | 418597001 | 0.780 ppm |
| 2018-12-03 | 422713001 | 0.800 ppm |
| 2018-12-03 | 422713001 | 0.841 ppm |
| 2019-01-03 | 428251001 | 0.760 ppm |
| 2019-01-03 | 428251001 | 0.837 ppm |
| 2019-02-15 | 432530001 | 0.720 ppm |
| 2019-02-15 | 432530001 | 0.751 ppm |
| 2019-03-15 | 436350001 | 0.700 ppm |
| 2019-03-15 | 436350001 | 0.722 ppm |
| 2019-04-04 | 440029001 | 0.690 ppm |
| 2019-04-04 | 440029001 | 0.740 ppm |
| 2019-05-10 | 446517001 | 0.760 ppm |
| 2019-05-10 | 446517001 | 0.773 ppm |
| 2019-06-05 | 450103001 | 0.750 ppm |
| 2019-06-05 | 450103001 | 0.760 ppm |
| 2019-07-15 | 460084001 | 0.740 ppm |
| 2019-07-15 | 460084001 | 0.774 ppm |
| 2019-08-09 | 464028001 | 0.756 ppm |
| 2019-08-09 | 464028001 | 0.760 ppm |
| 2019-09-10 | 471034001 | 0.760 ppm |
| 2019-09-10 | 471034001 | 0.777 ppm |
| 2019-10-16 | 477863001 | 0.720 ppm |
| 2019-10-16 | 477863001 | 0.768 ppm |
| 2019-11-12 | 482566001 | 0.770 ppm |
| 2019-11-12 | 482566001 | 0.799 ppm |
| 2019-12-12 | 487141001 | 0.710 ppm |
| 2019-12-12 | 487141001 | 0.724 ppm |