Fluoride
Williams Bay Waterworks
Fluoride occurs naturally in surface and groundwater and is also added to drinking water by many water systems to prevent cavities and support oral health in people.
In 2015, the Department of Health and Human Services updated its recommendation of an optimal level of 0.7 parts per million, or ppm, added to drinking water based on the health benefits of tooth decay prevention. Studies have shown that fluoride added to community water systems at this level reduces dental cavities, especially in children.
And studies have conclusively shown that fluoride in toothpaste and mouthwash can also provide these benefits.
Read More.
Health Concerns
Although the HHS-recommended level of 0.7 ppm can help promote oral health in children and adults, this level is likely too high for bottle-fed babies. EWG recommends that caregivers mix baby formula with fluoride-free water.
And fluoride in water at higher levels can be detrimental for everyone, especially children.
Long-term ingestion of higher levels of fluoride in water increases dental fluorosis, which includes mottling, pitting and weakening of the teeth in children.
A 2024 authoritative assessment by the National Toxicology Program found that higher levels of fluoride exposure, such as drinking water containing more than 1.5 ppm of fluoride, are associated with lower IQ in children. The conclusion was based on studies in human populations outside of the U.S.
Affecting systems with naturally occurring fluoride, 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 fracture. But these effects may occur at lower levels of exposure, raising concerns that the current limit may not adequately protect public health.
Samples
Samples exceeding legal limit (MCL)
Samples exceeding
health guidelines
Testing results - average by year
| Year | Average result | Samples taken | Detections | Range of results |
|---|---|---|---|---|
| 2018 | 0.711 ppm | 24 | 24 | 0.430 ppm - 0.830 ppm |
| 2019 | 0.743 ppm | 24 | 24 | 0.630 ppm - 0.830 ppm |
| 2020 | 0.710 ppm | 21 | 21 | 0.520 ppm - 0.910 ppm |
| 2021 | 0.714 ppm | 28 | 28 | 0.570 ppm - 0.833 ppm |
| 2022 | 0.650 ppm | 24 | 24 | 0.530 ppm - 0.835 ppm |
| 2023 | 0.722 ppm | 25 | 25 | 0.605 ppm - 0.963 ppm |
ppm = parts per million
State, National, and Health Guidelines for Drinking Water
EPA Maximum Contaminant
Level (MCL): 4 ppm
ppm = parts per million
All test results
| Date | Lab ID | Result |
|---|---|---|
| 2018-01-25 | 364453001 | 0.800 ppm |
| 2018-01-25 | 364453001 | 0.802 ppm |
| 2018-02-14 | 367063001 | 0.731 ppm |
| 2018-02-14 | 367063001 | 0.740 ppm |
| 2018-03-12 | 370818001 | 0.430 ppm |
| 2018-03-12 | 370818001 | 0.720 ppm |
| 2018-04-02 | 374720001 | 0.620 ppm |
| 2018-04-02 | 374720001 | 0.680 ppm |
| 2018-05-09 | 381304001 | 0.762 ppm |
| 2018-05-09 | 381304001 | 0.830 ppm |
| 2018-06-26 | 391203001 | 0.760 ppm |
| 2018-06-26 | 391203001 | 0.770 ppm |
| 2018-07-17 | 395260001 | 0.750 ppm |
| 2018-07-17 | 395260001 | 0.770 ppm |
| 2018-08-27 | 403793001 | 0.660 ppm |
| 2018-08-27 | 403793001 | 0.767 ppm |
| 2018-09-24 | 410574001 | 0.670 ppm |
| 2018-09-24 | 410574001 | 0.795 ppm |
| 2018-10-15 | 414656001 | 0.560 ppm |
| 2018-10-15 | 414656001 | 0.719 ppm |
| 2018-11-14 | 420311001 | 0.650 ppm |
| 2018-11-14 | 420311001 | 0.766 ppm |
| 2018-12-03 | 422382001 | 0.590 ppm |
| 2018-12-03 | 422382001 | 0.723 ppm |
| 2019-01-08 | 427256001 | 0.730 ppm |
| 2019-01-08 | 427256001 | 0.744 ppm |
| 2019-02-19 | 432327001 | 0.818 ppm |
| 2019-02-19 | 432327001 | 0.820 ppm |
| 2019-03-25 | 437359001 | 0.778 ppm |
| 2019-03-25 | 437359001 | 0.790 ppm |
| 2019-04-15 | 440689001 | 0.649 ppm |
| 2019-04-15 | 440689001 | 0.660 ppm |
| 2019-05-28 | 448424001 | 0.685 ppm |
| 2019-05-28 | 448424001 | 0.700 ppm |
| 2019-06-12 | 451478001 | 0.768 ppm |
| 2019-06-12 | 451478001 | 0.820 ppm |
| 2019-07-24 | 459950001 | 0.630 ppm |
| 2019-07-24 | 459950001 | 0.712 ppm |
| 2019-08-26 | 466436001 | 0.770 ppm |
| 2019-08-26 | 466436001 | 0.790 ppm |
| 2019-09-23 | 472129001 | 0.730 ppm |
| 2019-09-23 | 472129001 | 0.830 ppm |
| 2019-10-21 | 477532001 | 0.710 ppm |
| 2019-10-21 | 477532001 | 0.754 ppm |
| 2019-11-18 | 482561001 | 0.730 ppm |
| 2019-11-18 | 482561001 | 0.741 ppm |
| 2019-12-18 | 487193001 | 0.700 ppm |
| 2019-12-18 | 487193001 | 0.784 ppm |
| 2020-01-22 | 490640001 | 0.630 ppm |
| 2020-01-22 | 490640001 | 0.723 ppm |
| 2020-04-14 | 501079001 | 0.520 ppm |
| 2020-04-14 | 501079001 | 0.731 ppm |
| 2020-05-13 | 504823001 | 0.560 ppm |
| 2020-05-13 | 504823001 | 0.806 ppm |
| 2020-06-15 | 1193496 | 0.660 ppm |
| 2020-06-15 | 510245001 | 0.842 ppm |
| 2020-06-15 | 510245001 | 0.910 ppm |
| 2020-07-13 | 514866001 | 0.710 ppm |
| 2020-07-13 | 514866001 | 0.736 ppm |
| 2020-08-18 | 520888001 | 0.520 ppm |
| 2020-08-18 | 520888001 | 0.785 ppm |
| 2020-09-08 | 524307001 | 0.740 ppm |
| 2020-09-08 | 524307001 | 0.797 ppm |
| 2020-10-12 | 531535001 | 0.520 ppm |
| 2020-10-12 | 531535001 | 0.745 ppm |
| 2020-11-16 | 536901001 | 0.630 ppm |
| 2020-11-16 | 536901001 | 0.759 ppm |
| 2020-12-09 | 539975001 | 0.750 ppm |
| 2020-12-09 | 539975001 | 0.834 ppm |
| 2021-01-20 | 544742001 | 0.650 ppm |
| 2021-01-20 | 544742001 | 0.720 ppm |
| 2021-02-22 | 548520001 | 0.765 ppm |
| 2021-02-22 | 548520001 | 0.830 ppm |
| 2021-02-22 | 548520001 | 0.765 ppm |
| 2021-02-22 | 548520001 | 0.830 ppm |
| 2021-03-10 | 551559001 | 0.690 ppm |
| 2021-03-10 | 551559001 | 0.711 ppm |
| 2021-03-10 | 551559001 | 0.690 ppm |
| 2021-03-10 | 551559001 | 0.711 ppm |
| 2021-04-28 | 559185001 | 0.660 ppm |
| 2021-04-28 | 559185001 | 0.772 ppm |
| 2021-05-18 | 562966001 | 0.690 ppm |
| 2021-05-18 | 562966001 | 0.731 ppm |
| 2021-06-23 | 569235001 | 0.800 ppm |
| 2021-06-23 | 569235001 | 0.833 ppm |
| 2021-07-20 | 574218001 | 0.670 ppm |
| 2021-07-20 | 574218001 | 0.717 ppm |
| 2021-08-09 | 577898001 | 0.720 ppm |
| 2021-08-09 | 577898001 | 0.763 ppm |
| 2021-09-14 | 584337001 | 0.670 ppm |
| 2021-09-14 | 584337001 | 0.751 ppm |
| 2021-10-11 | 589695001 | 0.600 ppm |
| 2021-10-11 | 589695001 | 0.649 ppm |
| 2021-11-16 | 595258001 | 0.640 ppm |
| 2021-11-16 | 595258001 | 0.746 ppm |
| 2021-12-08 | 597928001 | 0.570 ppm |
| 2021-12-08 | 597928001 | 0.647 ppm |
| 2022-01-18 | 602751001 | 0.530 ppm |
| 2022-01-18 | 602751001 | 0.633 ppm |
| 2022-02-08 | 605468001 | 0.610 ppm |
| 2022-02-08 | 605468001 | 0.662 ppm |
| 2022-03-22 | 610748001 | 0.550 ppm |
| 2022-03-22 | 610748001 | 0.641 ppm |
| 2022-04-13 | 614083001 | 0.540 ppm |
| 2022-04-13 | 614083001 | 0.704 ppm |
| 2022-05-03 | 617537001 | 0.610 ppm |
| 2022-05-03 | 617537001 | 0.760 ppm |
| 2022-06-21 | 626735001 | 0.600 ppm |
| 2022-06-21 | 626735001 | 0.694 ppm |
| 2022-07-19 | 632324001 | 0.600 ppm |
| 2022-07-19 | 632324001 | 0.739 ppm |
| 2022-08-08 | 635748001 | 0.710 ppm |
| 2022-08-08 | 635748001 | 0.835 ppm |
| 2022-09-20 | 644002001 | 0.680 ppm |
| 2022-09-20 | 644002001 | 0.760 ppm |
| 2022-10-25 | 650520001 | 0.570 ppm |
| 2022-10-25 | 650520001 | 0.737 ppm |
| 2022-11-28 | 655186001 | 0.590 ppm |
| 2022-11-28 | 655186001 | 0.608 ppm |
| 2022-12-07 | 656613001 | 0.600 ppm |
| 2022-12-07 | 656613001 | 0.635 ppm |
| 2023-01-17 | 661226001 | 0.710 ppm |
| 2023-01-17 | 661226001 | 0.730 ppm |
| 2023-02-07 | 663917001 | 0.605 ppm |
| 2023-02-07 | 663917001 | 0.610 ppm |
| 2023-03-14 | 668744001 | 0.640 ppm |
| 2023-03-14 | 668744001 | 0.750 ppm |
| 2023-04-19 | 674164001 | 0.610 ppm |
| 2023-04-19 | 674164001 | 0.745 ppm |
| 2023-05-22 | 680413001 | 0.760 ppm |
| 2023-05-22 | 680413001 | 0.851 ppm |
| 2023-06-19 | 685744001 | 0.640 ppm |
| 2023-06-19 | 685744001 | 0.795 ppm |
| 2023-07-12 | 689018001 | 0.630 ppm |
| 2023-07-12 | 689018001 | 0.654 ppm |
| 2023-08-23 | 697034001 | 0.720 ppm |
| 2023-08-23 | WB05338-01 | 0.790 ppm |
| 2023-08-23 | 697034001 | 0.963 ppm |
| 2023-09-25 | 702819001 | 0.690 ppm |
| 2023-09-25 | 702819001 | 0.731 ppm |
| 2023-10-25 | 708215001 | 0.620 ppm |
| 2023-10-25 | 708215001 | 0.642 ppm |
| 2023-11-13 | 711090001 | 0.700 ppm |
| 2023-11-13 | 711090001 | 0.785 ppm |
| 2023-12-12 | 714610001 | 0.780 ppm |
| 2023-12-12 | 714610001 | 0.887 ppm |