Fluoride
Oconomowoc 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 | 0.677 ppm | 28 | 28 | 0.120 ppm - 0.800 ppm |
| 2015 | 0.714 ppm | 24 | 24 | 0.565 ppm - 0.835 ppm |
| 2016 | 0.718 ppm | 24 | 24 | 0.589 ppm - 0.886 ppm |
| 2017 | 0.740 ppm | 28 | 28 | 0.571 ppm - 1.10 ppm |
| 2018 | 0.703 ppm | 24 | 24 | 0.578 ppm - 0.817 ppm |
| 2019 | 0.715 ppm | 24 | 24 | 0.617 ppm - 0.803 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 |
|---|---|---|
| 2014-01-05 | 114950001 | 0.750 ppm |
| 2014-01-05 | 114950001 | 0.800 ppm |
| 2014-02-02 | 118110001 | 0.672 ppm |
| 2014-02-02 | 118110001 | 0.750 ppm |
| 2014-03-06 | 122264001 | 0.690 ppm |
| 2014-03-06 | 122264001 | 0.715 ppm |
| 2014-04-09 | 127315001 | 0.710 ppm |
| 2014-04-09 | 127315001 | 0.710 ppm |
| 2014-05-05 | 131171001 | 0.685 ppm |
| 2014-05-05 | 131171001 | 0.720 ppm |
| 2014-06-03 | 794042 | 0.570 ppm |
| 2014-06-03 | 794046 | 0.610 ppm |
| 2014-06-03 | 794044 | 0.670 ppm |
| 2014-06-12 | 139050001 | 0.616 ppm |
| 2014-06-12 | 139050001 | 0.740 ppm |
| 2014-07-07 | 801199 | 0.120 ppm |
| 2014-07-11 | 145133001 | 0.700 ppm |
| 2014-07-11 | 145133001 | 0.751 ppm |
| 2014-08-13 | 151503001 | 0.730 ppm |
| 2014-08-13 | 151503001 | 0.736 ppm |
| 2014-09-07 | 155745001 | 0.713 ppm |
| 2014-09-07 | 155745001 | 0.720 ppm |
| 2014-10-07 | 162933001 | 0.703 ppm |
| 2014-10-07 | 162933001 | 0.720 ppm |
| 2014-11-12 | 168519001 | 0.639 ppm |
| 2014-11-12 | 168519001 | 0.730 ppm |
| 2014-12-04 | 171310001 | 0.591 ppm |
| 2014-12-04 | 171310001 | 0.700 ppm |
| 2015-01-09 | 175164001 | 0.720 ppm |
| 2015-01-09 | 175164001 | 0.749 ppm |
| 2015-02-06 | 178945001 | 0.700 ppm |
| 2015-02-06 | 178945001 | 0.732 ppm |
| 2015-03-09 | 183013001 | 0.700 ppm |
| 2015-03-09 | 183013001 | 0.778 ppm |
| 2015-04-08 | 187286001 | 0.740 ppm |
| 2015-04-08 | 187286001 | 0.744 ppm |
| 2015-05-13 | 193837001 | 0.720 ppm |
| 2015-05-13 | 193837001 | 0.835 ppm |
| 2015-06-09 | 199213001 | 0.610 ppm |
| 2015-06-09 | 199213001 | 0.811 ppm |
| 2015-07-29 | 208923001 | 0.700 ppm |
| 2015-07-29 | 208923001 | 0.712 ppm |
| 2015-08-12 | 211855001 | 0.700 ppm |
| 2015-08-12 | 211855001 | 0.710 ppm |
| 2015-09-01 | 215569001 | 0.679 ppm |
| 2015-09-01 | 215569001 | 0.710 ppm |
| 2015-10-05 | 222493001 | 0.630 ppm |
| 2015-10-05 | 222493001 | 0.686 ppm |
| 2015-11-09 | 228313001 | 0.720 ppm |
| 2015-11-09 | 228313001 | 0.785 ppm |
| 2015-12-04 | 231562001 | 0.565 ppm |
| 2015-12-04 | 231562001 | 0.700 ppm |
| 2016-01-08 | 235310001 | 0.589 ppm |
| 2016-01-08 | 235310001 | 0.680 ppm |
| 2016-02-08 | 239480001 | 0.700 ppm |
| 2016-02-08 | 239480001 | 0.886 ppm |
| 2016-03-08 | 243626001 | 0.650 ppm |
| 2016-03-08 | 243626001 | 0.705 ppm |
| 2016-04-08 | 248134001 | 0.650 ppm |
| 2016-04-08 | 248134001 | 0.717 ppm |
| 2016-05-04 | 252817001 | 0.680 ppm |
| 2016-05-04 | 252817001 | 0.709 ppm |
| 2016-06-17 | 261059001 | 0.690 ppm |
| 2016-06-17 | 261059001 | 0.756 ppm |
| 2016-07-13 | 266322001 | 0.709 ppm |
| 2016-07-13 | 266322001 | 0.710 ppm |
| 2016-08-08 | 271774001 | 0.720 ppm |
| 2016-08-08 | 271774001 | 0.754 ppm |
| 2016-09-08 | 277122001 | 0.750 ppm |
| 2016-09-08 | 277122001 | 0.772 ppm |
| 2016-10-12 | 284044001 | 0.720 ppm |
| 2016-10-12 | 284044001 | 0.756 ppm |
| 2016-11-07 | 288666001 | 0.730 ppm |
| 2016-11-07 | 288666001 | 0.796 ppm |
| 2016-12-03 | 291387001 | 0.691 ppm |
| 2016-12-03 | 291387001 | 0.720 ppm |
| 2017-01-06 | 295636001 | 0.720 ppm |
| 2017-01-06 | 295636001 | 0.769 ppm |
| 2017-02-08 | 299540001 | 0.720 ppm |
| 2017-02-08 | 299540001 | 0.819 ppm |
| 2017-02-21 | 974595 | 0.640 ppm |
| 2017-02-21 | 974607 | 0.730 ppm |
| 2017-02-21 | 974603 | 0.790 ppm |
| 2017-02-21 | 974599 | 1.10 ppm |
| 2017-03-31 | 306997001 | 0.730 ppm |
| 2017-03-31 | 306997001 | 0.799 ppm |
| 2017-04-10 | 309456001 | 0.740 ppm |
| 2017-04-10 | 309456001 | 0.775 ppm |
| 2017-05-01 | 313456001 | 0.740 ppm |
| 2017-05-01 | 313456001 | 0.820 ppm |
| 2017-06-06 | 320524001 | 0.670 ppm |
| 2017-06-06 | 320524001 | 0.721 ppm |
| 2017-07-05 | 326050001 | 0.713 ppm |
| 2017-07-05 | 326050001 | 0.720 ppm |
| 2017-08-29 | 339182001 | 0.690 ppm |
| 2017-08-29 | 339182001 | 0.718 ppm |
| 2017-09-16 | 343207001 | 0.690 ppm |
| 2017-09-16 | 343207001 | 0.710 ppm |
| 2017-10-05 | 347368001 | 0.750 ppm |
| 2017-10-05 | 347368001 | 0.759 ppm |
| 2017-11-02 | 352272001 | 0.571 ppm |
| 2017-11-02 | 352272001 | 0.710 ppm |
| 2017-12-05 | 358086001 | 0.708 ppm |
| 2017-12-05 | 358086001 | 0.710 ppm |
| 2018-01-05 | 362510001 | 0.700 ppm |
| 2018-01-05 | 362510001 | 0.710 ppm |
| 2018-02-01 | 365116001 | 0.700 ppm |
| 2018-02-01 | 365116001 | 0.709 ppm |
| 2018-03-06 | 370312001 | 0.690 ppm |
| 2018-03-06 | 370312001 | 0.745 ppm |
| 2018-04-06 | 375813001 | 0.690 ppm |
| 2018-04-06 | 375813001 | 0.744 ppm |
| 2018-05-01 | 379774001 | 0.578 ppm |
| 2018-05-01 | 379774001 | 0.680 ppm |
| 2018-06-14 | 389597001 | 0.659 ppm |
| 2018-06-14 | 389597001 | 0.690 ppm |
| 2018-07-09 | 393593001 | 0.710 ppm |
| 2018-07-09 | 393593001 | 0.801 ppm |
| 2018-08-14 | 401333001 | 0.710 ppm |
| 2018-08-14 | 401333001 | 0.817 ppm |
| 2018-09-13 | 408409001 | 0.660 ppm |
| 2018-09-13 | 408409001 | 0.812 ppm |
| 2018-10-04 | 412722001 | 0.700 ppm |
| 2018-10-04 | 412722001 | 0.710 ppm |
| 2018-11-02 | 418111001 | 0.642 ppm |
| 2018-11-02 | 418111001 | 0.680 ppm |
| 2018-12-05 | 423026001 | 0.633 ppm |
| 2018-12-05 | 423026001 | 0.690 ppm |
| 2019-01-07 | 427073001 | 0.617 ppm |
| 2019-01-07 | 427073001 | 0.680 ppm |
| 2019-02-05 | 430716001 | 0.664 ppm |
| 2019-02-05 | 430716001 | 0.680 ppm |
| 2019-03-05 | 434234001 | 0.657 ppm |
| 2019-03-05 | 434234001 | 0.740 ppm |
| 2019-04-08 | 439825001 | 0.660 ppm |
| 2019-04-08 | 439825001 | 0.685 ppm |
| 2019-05-15 | 446670001 | 0.690 ppm |
| 2019-05-15 | 446670001 | 0.743 ppm |
| 2019-06-06 | 450986001 | 0.700 ppm |
| 2019-06-06 | 450986001 | 0.725 ppm |
| 2019-07-02 | 455493001 | 0.710 ppm |
| 2019-07-02 | 455493001 | 0.745 ppm |
| 2019-08-05 | 462451001 | 0.730 ppm |
| 2019-08-05 | 462451001 | 0.772 ppm |
| 2019-09-05 | 468109001 | 0.720 ppm |
| 2019-09-05 | 468109001 | 0.788 ppm |
| 2019-10-07 | 475459001 | 0.730 ppm |
| 2019-10-07 | 475459001 | 0.781 ppm |
| 2019-11-04 | 480032001 | 0.670 ppm |
| 2019-11-04 | 480032001 | 0.779 ppm |
| 2019-12-03 | 484709001 | 0.680 ppm |
| 2019-12-03 | 484709001 | 0.803 ppm |