Fluoride
Monona 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 | 0.745 ppm | 27 | 27 | 0.114 ppm - 1.01 ppm |
| 2015 | 0.739 ppm | 24 | 24 | 0.330 ppm - 1.08 ppm |
| 2016 | 0.519 ppm | 24 | 24 | 0.400 ppm - 0.670 ppm |
| 2017 | 0.618 ppm | 27 | 27 | 0.500 ppm - 0.810 ppm |
| 2018 | 0.677 ppm | 24 | 24 | 0.570 ppm - 0.830 ppm |
| 2019 | 0.679 ppm | 24 | 24 | 0.510 ppm - 0.830 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 |
|---|---|---|
| 2014-01-07 | 115028001 | 0.740 ppm |
| 2014-01-07 | 115028001 | 0.785 ppm |
| 2014-02-21 | 120503001 | 0.784 ppm |
| 2014-02-21 | 120503001 | 0.990 ppm |
| 2014-03-10 | 122284001 | 0.830 ppm |
| 2014-03-10 | 122284001 | 0.940 ppm |
| 2014-04-18 | 128259001 | 0.793 ppm |
| 2014-04-18 | 128259001 | 0.930 ppm |
| 2014-05-08 | 131344001 | 0.678 ppm |
| 2014-05-08 | 131344001 | 0.810 ppm |
| 2014-06-13 | 139014001 | 0.711 ppm |
| 2014-06-13 | 139014001 | 0.770 ppm |
| 2014-07-25 | 147550001 | 0.794 ppm |
| 2014-07-25 | 147550001 | 0.860 ppm |
| 2014-08-13 | 151185001 | 0.799 ppm |
| 2014-08-13 | 151185001 | 1.01 ppm |
| 2014-09-02 | 154277001 | 0.114 ppm |
| 2014-09-02 | 154327001 | 0.129 ppm |
| 2014-09-02 | 154324001 | 0.791 ppm |
| 2014-09-02 | 154324001 | 0.850 ppm |
| 2014-09-05 | 155124001 | 0.130 ppm |
| 2014-10-14 | 163107001 | 0.800 ppm |
| 2014-10-14 | 163107001 | 0.819 ppm |
| 2014-11-03 | 166331001 | 0.784 ppm |
| 2014-11-03 | 166331001 | 0.820 ppm |
| 2014-12-03 | 170972001 | 0.813 ppm |
| 2014-12-03 | 170972001 | 0.850 ppm |
| 2015-01-15 | 175909001 | 0.817 ppm |
| 2015-01-15 | 175909001 | 0.850 ppm |
| 2015-02-12 | 179577001 | 0.825 ppm |
| 2015-02-12 | 179577001 | 0.880 ppm |
| 2015-03-16 | 183476001 | 0.852 ppm |
| 2015-03-16 | 183476001 | 1.02 ppm |
| 2015-04-03 | 185923001 | 0.830 ppm |
| 2015-04-03 | 185923001 | 0.850 ppm |
| 2015-05-11 | 192269001 | 0.740 ppm |
| 2015-05-11 | 192269001 | 0.791 ppm |
| 2015-06-15 | 199453001 | 0.730 ppm |
| 2015-06-15 | 199453001 | 0.848 ppm |
| 2015-07-07 | 203825001 | 0.860 ppm |
| 2015-07-07 | 203825001 | 0.880 ppm |
| 2015-08-17 | 211955001 | 0.926 ppm |
| 2015-08-17 | 211955001 | 1.08 ppm |
| 2015-09-16 | 217968001 | 0.680 ppm |
| 2015-09-16 | 217968001 | 0.680 ppm |
| 2015-10-12 | 223038001 | 0.330 ppm |
| 2015-10-12 | 223038001 | 0.410 ppm |
| 2015-11-17 | 228881001 | 0.435 ppm |
| 2015-11-17 | 228881001 | 0.480 ppm |
| 2015-12-18 | 233323001 | 0.423 ppm |
| 2015-12-18 | 233323001 | 0.510 ppm |
| 2016-01-25 | 236876001 | 0.607 ppm |
| 2016-01-25 | 236876001 | 0.670 ppm |
| 2016-02-17 | 240130001 | 0.473 ppm |
| 2016-02-17 | 240130001 | 0.590 ppm |
| 2016-03-14 | 243657001 | 0.420 ppm |
| 2016-03-14 | 243657001 | 0.440 ppm |
| 2016-04-27 | 251018001 | 0.451 ppm |
| 2016-04-27 | 251018001 | 0.630 ppm |
| 2016-05-16 | 254323001 | 0.495 ppm |
| 2016-05-16 | 254323001 | 0.590 ppm |
| 2016-06-13 | 259617001 | 0.463 ppm |
| 2016-06-13 | 259617001 | 0.610 ppm |
| 2016-07-21 | 267725001 | 0.441 ppm |
| 2016-07-21 | 267725001 | 0.580 ppm |
| 2016-08-16 | 272278001 | 0.400 ppm |
| 2016-08-16 | 272278001 | 0.590 ppm |
| 2016-09-22 | 279708001 | 0.440 ppm |
| 2016-09-22 | 279708001 | 0.490 ppm |
| 2016-10-28 | 286316001 | 0.457 ppm |
| 2016-10-28 | 286316001 | 0.490 ppm |
| 2016-11-18 | 289740001 | 0.416 ppm |
| 2016-11-18 | 289740001 | 0.510 ppm |
| 2016-12-20 | 293762001 | 0.568 ppm |
| 2016-12-20 | 293762001 | 0.630 ppm |
| 2017-01-23 | 296978001 | 0.638 ppm |
| 2017-01-23 | 296978001 | 0.730 ppm |
| 2017-02-17 | 300562001 | 0.707 ppm |
| 2017-02-17 | 300562001 | 0.810 ppm |
| 2017-03-15 | 304303001 | 0.525 ppm |
| 2017-03-15 | 304303001 | 0.580 ppm |
| 2017-04-13 | 309629001 | 0.543 ppm |
| 2017-04-13 | 309629003 | 0.544 ppm |
| 2017-04-13 | 309629002 | 0.606 ppm |
| 2017-04-27 | 312217001 | 0.500 ppm |
| 2017-04-27 | 312217001 | 0.547 ppm |
| 2017-05-08 | 314075001 | 0.536 ppm |
| 2017-05-08 | 314075001 | 0.670 ppm |
| 2017-06-05 | 319218001 | 0.668 ppm |
| 2017-06-05 | 319218001 | 0.750 ppm |
| 2017-07-03 | 325659001 | 0.536 ppm |
| 2017-07-03 | 325659001 | 0.600 ppm |
| 2017-08-02 | 332682001 | 0.510 ppm |
| 2017-08-02 | 332682001 | 0.598 ppm |
| 2017-09-14 | 342265001 | 0.578 ppm |
| 2017-09-14 | 342265001 | 0.600 ppm |
| 2017-10-10 | 347701001 | 0.540 ppm |
| 2017-10-10 | 347701001 | 0.562 ppm |
| 2017-11-15 | 354727001 | 0.641 ppm |
| 2017-11-15 | 354727001 | 0.690 ppm |
| 2017-12-12 | 358868001 | 0.694 ppm |
| 2017-12-12 | 358868001 | 0.770 ppm |
| 2018-01-30 | 364667001 | 0.656 ppm |
| 2018-01-30 | 364667001 | 0.670 ppm |
| 2018-02-13 | 366667001 | 0.640 ppm |
| 2018-02-13 | 366667001 | 0.674 ppm |
| 2018-03-05 | 369181001 | 0.696 ppm |
| 2018-03-05 | 369181001 | 0.830 ppm |
| 2018-04-02 | 373735001 | 0.674 ppm |
| 2018-04-02 | 373735001 | 0.690 ppm |
| 2018-05-07 | 379970001 | 0.703 ppm |
| 2018-05-07 | 379970001 | 0.710 ppm |
| 2018-06-20 | 389965001 | 0.659 ppm |
| 2018-06-20 | 389965001 | 0.690 ppm |
| 2018-07-19 | 395680001 | 0.650 ppm |
| 2018-07-19 | 395680001 | 0.730 ppm |
| 2018-08-03 | 398480001 | 0.675 ppm |
| 2018-08-03 | 398480001 | 0.740 ppm |
| 2018-09-19 | 409015001 | 0.570 ppm |
| 2018-09-19 | 409015001 | 0.633 ppm |
| 2018-10-24 | 416245001 | 0.600 ppm |
| 2018-10-24 | 416245001 | 0.675 ppm |
| 2018-11-06 | 418108001 | 0.653 ppm |
| 2018-11-06 | 418108001 | 0.710 ppm |
| 2018-12-05 | 422695001 | 0.592 ppm |
| 2018-12-05 | 422695001 | 0.720 ppm |
| 2019-01-15 | 427843001 | 0.618 ppm |
| 2019-01-15 | 427843001 | 0.730 ppm |
| 2019-02-20 | 432340001 | 0.699 ppm |
| 2019-02-20 | 432340001 | 0.830 ppm |
| 2019-03-07 | 434246001 | 0.741 ppm |
| 2019-03-07 | 434246001 | 0.760 ppm |
| 2019-04-03 | 438548001 | 0.676 ppm |
| 2019-04-03 | 438548001 | 0.720 ppm |
| 2019-05-08 | 444792001 | 0.660 ppm |
| 2019-05-08 | 444792001 | 0.790 ppm |
| 2019-06-05 | 449993001 | 0.694 ppm |
| 2019-06-05 | 449993001 | 0.770 ppm |
| 2019-07-08 | 455630001 | 0.599 ppm |
| 2019-07-08 | 455630001 | 0.610 ppm |
| 2019-08-28 | 466437001 | 0.619 ppm |
| 2019-08-28 | 466437001 | 0.660 ppm |
| 2019-09-05 | 467858001 | 0.663 ppm |
| 2019-09-05 | 467858001 | 0.770 ppm |
| 2019-10-16 | 476627001 | 0.510 ppm |
| 2019-10-16 | 476627001 | 0.627 ppm |
| 2019-11-07 | 480311001 | 0.613 ppm |
| 2019-11-07 | 480311001 | 0.740 ppm |
| 2019-12-04 | 484316001 | 0.570 ppm |
| 2019-12-04 | 484316001 | 0.622 ppm |