Fluoride
Colby 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 | 0.672 ppm | 24 | 24 | 0.520 ppm - 0.770 ppm |
| 2019 | 0.668 ppm | 24 | 24 | 0.547 ppm - 0.750 ppm |
| 2020 | 0.681 ppm | 22 | 22 | 0.597 ppm - 0.740 ppm |
| 2021 | 0.678 ppm | 28 | 28 | 0.624 ppm - 0.730 ppm |
| 2022 | 0.691 ppm | 24 | 24 | 0.650 ppm - 0.723 ppm |
| 2023 | 0.695 ppm | 26 | 26 | 0.650 ppm - 0.751 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 |
|---|---|---|
| 2018-01-08 | 361969001 | 0.660 ppm |
| 2018-01-08 | 361969001 | 0.665 ppm |
| 2018-02-07 | 366117001 | 0.698 ppm |
| 2018-02-07 | 366117001 | 0.740 ppm |
| 2018-03-07 | 370311001 | 0.720 ppm |
| 2018-03-07 | 370311001 | 0.739 ppm |
| 2018-04-06 | 375393001 | 0.618 ppm |
| 2018-04-06 | 375393001 | 0.680 ppm |
| 2018-05-10 | 382147001 | 0.694 ppm |
| 2018-05-10 | 382147001 | 0.710 ppm |
| 2018-06-08 | 387918001 | 0.634 ppm |
| 2018-06-08 | 387918001 | 0.690 ppm |
| 2018-07-27 | 397817001 | 0.611 ppm |
| 2018-07-27 | 397817001 | 0.670 ppm |
| 2018-08-15 | 401716001 | 0.567 ppm |
| 2018-08-15 | 401716001 | 0.750 ppm |
| 2018-09-11 | 407770001 | 0.520 ppm |
| 2018-09-11 | 407770001 | 0.760 ppm |
| 2018-10-02 | 412543001 | 0.643 ppm |
| 2018-10-02 | 412543001 | 0.770 ppm |
| 2018-11-09 | 419871001 | 0.560 ppm |
| 2018-11-09 | 419871001 | 0.710 ppm |
| 2018-12-05 | 423987001 | 0.593 ppm |
| 2018-12-05 | 423987001 | 0.730 ppm |
| 2019-01-02 | 426104001 | 0.658 ppm |
| 2019-01-02 | 426104001 | 0.700 ppm |
| 2019-02-08 | 432528001 | 0.706 ppm |
| 2019-02-08 | 432528001 | 0.730 ppm |
| 2019-03-05 | 434421001 | 0.715 ppm |
| 2019-03-05 | 434421001 | 0.730 ppm |
| 2019-04-02 | 438792001 | 0.668 ppm |
| 2019-04-02 | 438792001 | 0.710 ppm |
| 2019-05-06 | 445214001 | 0.667 ppm |
| 2019-05-06 | 445214001 | 0.750 ppm |
| 2019-06-10 | 451890001 | 0.700 ppm |
| 2019-06-10 | 451890001 | 0.741 ppm |
| 2019-07-16 | 458428001 | 0.592 ppm |
| 2019-07-16 | 458428001 | 0.650 ppm |
| 2019-08-05 | 462201001 | 0.654 ppm |
| 2019-08-05 | 462201001 | 0.680 ppm |
| 2019-09-06 | 468049001 | 0.572 ppm |
| 2019-09-06 | 468049001 | 0.660 ppm |
| 2019-10-01 | 474310001 | 0.615 ppm |
| 2019-10-01 | 474310001 | 0.660 ppm |
| 2019-11-06 | 480538001 | 0.578 ppm |
| 2019-11-06 | 480538001 | 0.700 ppm |
| 2019-12-13 | 486023001 | 0.547 ppm |
| 2019-12-13 | 486023001 | 0.660 ppm |
| 2020-01-07 | 488476001 | 0.597 ppm |
| 2020-01-07 | 488476001 | 0.690 ppm |
| 2020-04-03 | 499780001 | 0.680 ppm |
| 2020-04-03 | 499780001 | 0.691 ppm |
| 2020-04-21 | 1184259 | 0.640 ppm |
| 2020-04-21 | 1184258 | 0.660 ppm |
| 2020-05-05 | 503503001 | 0.665 ppm |
| 2020-05-05 | 503503001 | 0.740 ppm |
| 2020-06-01 | 507803001 | 0.684 ppm |
| 2020-06-01 | 507803001 | 0.710 ppm |
| 2020-07-08 | 513924001 | 0.660 ppm |
| 2020-07-08 | 513924001 | 0.734 ppm |
| 2020-08-04 | 518471001 | 0.632 ppm |
| 2020-08-04 | 518471001 | 0.690 ppm |
| 2020-09-02 | 523651001 | 0.696 ppm |
| 2020-09-02 | 523651001 | 0.740 ppm |
| 2020-10-05 | 530317001 | 0.692 ppm |
| 2020-10-05 | 530317001 | 0.700 ppm |
| 2020-11-03 | 534817001 | 0.597 ppm |
| 2020-11-03 | 534817001 | 0.710 ppm |
| 2020-12-01 | 538612001 | 0.635 ppm |
| 2020-12-01 | 538612001 | 0.730 ppm |
| 2021-01-05 | 542666001 | 0.664 ppm |
| 2021-01-05 | 542666001 | 0.710 ppm |
| 2021-02-01 | 546258001 | 0.631 ppm |
| 2021-02-01 | 546258001 | 0.710 ppm |
| 2021-02-01 | 546258001 | 0.631 ppm |
| 2021-02-01 | 546258001 | 0.710 ppm |
| 2021-03-02 | 549882001 | 0.624 ppm |
| 2021-03-02 | 549882001 | 0.670 ppm |
| 2021-03-02 | 549882001 | 0.624 ppm |
| 2021-03-02 | 549882001 | 0.670 ppm |
| 2021-04-06 | 555275001 | 0.661 ppm |
| 2021-04-06 | 555275001 | 0.710 ppm |
| 2021-05-05 | 560511001 | 0.669 ppm |
| 2021-05-05 | 560511001 | 0.700 ppm |
| 2021-06-01 | 564922001 | 0.660 ppm |
| 2021-06-01 | 564922001 | 0.700 ppm |
| 2021-07-09 | 571355001 | 0.650 ppm |
| 2021-07-09 | 571355001 | 0.708 ppm |
| 2021-08-04 | 576533001 | 0.655 ppm |
| 2021-08-04 | 576533001 | 0.690 ppm |
| 2021-09-13 | 584879001 | 0.674 ppm |
| 2021-09-13 | 584879001 | 0.710 ppm |
| 2021-10-06 | 589698001 | 0.651 ppm |
| 2021-10-06 | 589698001 | 0.700 ppm |
| 2021-11-01 | 593195001 | 0.681 ppm |
| 2021-11-01 | 593195001 | 0.730 ppm |
| 2021-12-07 | 597930001 | 0.669 ppm |
| 2021-12-07 | 597930001 | 0.710 ppm |
| 2022-01-04 | 601003001 | 0.680 ppm |
| 2022-01-04 | 601003001 | 0.682 ppm |
| 2022-02-03 | 604551001 | 0.664 ppm |
| 2022-02-03 | 604551001 | 0.700 ppm |
| 2022-03-03 | 608116001 | 0.680 ppm |
| 2022-03-03 | 608116001 | 0.720 ppm |
| 2022-04-05 | 612733001 | 0.656 ppm |
| 2022-04-05 | 612733001 | 0.700 ppm |
| 2022-05-03 | 617546001 | 0.685 ppm |
| 2022-05-03 | 617546001 | 0.700 ppm |
| 2022-06-01 | 622719001 | 0.650 ppm |
| 2022-06-01 | 622719001 | 0.653 ppm |
| 2022-07-11 | 630401001 | 0.710 ppm |
| 2022-07-11 | 630401001 | 0.710 ppm |
| 2022-08-02 | 635051001 | 0.720 ppm |
| 2022-08-02 | 635051001 | 0.723 ppm |
| 2022-09-13 | 642540001 | 0.704 ppm |
| 2022-09-13 | 642540001 | 0.710 ppm |
| 2022-10-05 | 647292001 | 0.689 ppm |
| 2022-10-05 | 647292001 | 0.690 ppm |
| 2022-11-01 | 651760001 | 0.700 ppm |
| 2022-11-01 | 651760001 | 0.712 ppm |
| 2022-12-05 | 656189001 | 0.658 ppm |
| 2022-12-05 | 656189001 | 0.680 ppm |
| 2023-01-09 | 660042001 | 0.710 ppm |
| 2023-01-09 | 660042001 | 0.717 ppm |
| 2023-02-06 | 664431001 | 0.720 ppm |
| 2023-02-06 | 664431001 | 0.751 ppm |
| 2023-03-06 | 667783001 | 0.663 ppm |
| 2023-03-06 | 667783001 | 0.740 ppm |
| 2023-04-07 | 672767001 | 0.678 ppm |
| 2023-04-07 | 672767001 | 0.700 ppm |
| 2023-05-01 | 676678001 | 0.672 ppm |
| 2023-05-01 | 676678001 | 0.720 ppm |
| 2023-06-06 | 682894001 | 0.656 ppm |
| 2023-06-06 | 682894001 | 0.720 ppm |
| 2023-07-11 | 689981001 | 0.660 ppm |
| 2023-07-11 | 689981001 | 0.691 ppm |
| 2023-07-25 | CB08518-01 | 0.650 ppm |
| 2023-07-25 | CB08518-05 | 0.690 ppm |
| 2023-08-07 | 694079001 | 0.670 ppm |
| 2023-08-07 | 694079001 | 0.722 ppm |
| 2023-09-06 | 699148001 | 0.668 ppm |
| 2023-09-06 | 699148001 | 0.740 ppm |
| 2023-10-06 | 704897001 | 0.650 ppm |
| 2023-10-06 | 704897001 | 0.669 ppm |
| 2023-11-03 | 709907001 | 0.720 ppm |
| 2023-11-03 | 709907001 | 0.730 ppm |
| 2023-12-04 | 713997001 | 0.684 ppm |
| 2023-12-04 | 713997001 | 0.690 ppm |