Fluoride
City of Beloit
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 |
|---|---|---|---|---|
| 2013 | N/A | 0 | 0 | N/A |
| 2014 | 0.609 ppm | 31 | 31 | 0.0770 ppm - 0.900 ppm |
| 2015 | 0.810 ppm | 24 | 24 | 0.641 ppm - 0.970 ppm |
| 2016 | 0.830 ppm | 24 | 24 | 0.740 ppm - 0.940 ppm |
| 2017 | 0.678 ppm | 31 | 31 | 0.0980 ppm - 0.990 ppm |
| 2018 | 0.888 ppm | 24 | 24 | 0.750 ppm - 0.954 ppm |
| 2019 | 0.835 ppm | 24 | 24 | 0.650 ppm - 0.990 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 |
|---|---|---|
| 2014-01-13 | 115711001 | 0.804 ppm |
| 2014-01-13 | 115711001 | 0.850 ppm |
| 2014-02-10 | 119070001 | 0.750 ppm |
| 2014-02-10 | 119070001 | 0.830 ppm |
| 2014-02-26 | 772241 | 0.0770 ppm |
| 2014-02-26 | 772247 | 0.0790 ppm |
| 2014-02-26 | 772244 | 0.0900 ppm |
| 2014-02-26 | 772255 | 0.1000 ppm |
| 2014-02-26 | 772249 | 0.1000 ppm |
| 2014-02-26 | 772251 | 0.140 ppm |
| 2014-02-26 | 772257 | 0.610 ppm |
| 2014-03-10 | 122460001 | 0.803 ppm |
| 2014-03-10 | 122460001 | 0.900 ppm |
| 2014-04-01 | 125521001 | 0.604 ppm |
| 2014-04-01 | 125521001 | 0.710 ppm |
| 2014-05-06 | 131136001 | 0.660 ppm |
| 2014-05-06 | 131136001 | 0.740 ppm |
| 2014-06-12 | 139016001 | 0.620 ppm |
| 2014-06-12 | 139016001 | 0.664 ppm |
| 2014-07-09 | 144472001 | 0.700 ppm |
| 2014-07-09 | 144472001 | 0.752 ppm |
| 2014-08-07 | 150111001 | 0.740 ppm |
| 2014-08-07 | 150111001 | 0.758 ppm |
| 2014-09-11 | 156806001 | 0.657 ppm |
| 2014-09-11 | 156806001 | 0.740 ppm |
| 2014-10-13 | 163722001 | 0.687 ppm |
| 2014-10-13 | 163722001 | 0.750 ppm |
| 2014-11-11 | 168220001 | 0.704 ppm |
| 2014-11-11 | 168220001 | 0.720 ppm |
| 2014-12-08 | 171513001 | 0.767 ppm |
| 2014-12-08 | 171513001 | 0.780 ppm |
| 2015-01-13 | 175599001 | 0.641 ppm |
| 2015-01-13 | 175599001 | 0.720 ppm |
| 2015-02-04 | 178434001 | 0.811 ppm |
| 2015-02-04 | 178434001 | 0.920 ppm |
| 2015-03-05 | 182278001 | 0.900 ppm |
| 2015-03-05 | 182278001 | 0.909 ppm |
| 2015-04-09 | 187317001 | 0.719 ppm |
| 2015-04-09 | 187317001 | 0.800 ppm |
| 2015-05-12 | 193220001 | 0.720 ppm |
| 2015-05-12 | 193220001 | 0.720 ppm |
| 2015-06-10 | 199210001 | 0.710 ppm |
| 2015-06-10 | 199210001 | 0.779 ppm |
| 2015-07-07 | 204254001 | 0.780 ppm |
| 2015-07-07 | 204254001 | 0.832 ppm |
| 2015-08-12 | 211519001 | 0.810 ppm |
| 2015-08-12 | 211519001 | 0.812 ppm |
| 2015-09-09 | 216562001 | 0.829 ppm |
| 2015-09-09 | 216562001 | 0.840 ppm |
| 2015-10-09 | 222975001 | 0.780 ppm |
| 2015-10-09 | 222975001 | 0.842 ppm |
| 2015-11-02 | 226760001 | 0.820 ppm |
| 2015-11-02 | 226760001 | 0.911 ppm |
| 2015-12-08 | 232238001 | 0.860 ppm |
| 2015-12-08 | 232238001 | 0.970 ppm |
| 2016-01-11 | 235298001 | 0.740 ppm |
| 2016-01-11 | 235298001 | 0.888 ppm |
| 2016-02-03 | 238386001 | 0.860 ppm |
| 2016-02-03 | 238386001 | 0.940 ppm |
| 2016-03-11 | 244453001 | 0.854 ppm |
| 2016-03-11 | 244453001 | 0.920 ppm |
| 2016-04-05 | 247515001 | 0.780 ppm |
| 2016-04-05 | 247515001 | 0.865 ppm |
| 2016-05-09 | 253878001 | 0.848 ppm |
| 2016-05-09 | 253878001 | 0.850 ppm |
| 2016-06-13 | 260365001 | 0.770 ppm |
| 2016-06-13 | 260365001 | 0.828 ppm |
| 2016-07-12 | 266197001 | 0.809 ppm |
| 2016-07-12 | 266197001 | 0.850 ppm |
| 2016-08-09 | 271624001 | 0.800 ppm |
| 2016-08-09 | 271624001 | 0.821 ppm |
| 2016-09-16 | 278141001 | 0.792 ppm |
| 2016-09-16 | 278141001 | 0.860 ppm |
| 2016-10-11 | 283874001 | 0.790 ppm |
| 2016-10-11 | 283874001 | 0.796 ppm |
| 2016-11-02 | 287323001 | 0.799 ppm |
| 2016-11-02 | 287323001 | 0.870 ppm |
| 2016-12-13 | 293110001 | 0.775 ppm |
| 2016-12-13 | 293110001 | 0.820 ppm |
| 2017-01-10 | 296073001 | 0.818 ppm |
| 2017-01-10 | 296073001 | 0.850 ppm |
| 2017-02-13 | 299886001 | 0.600 ppm |
| 2017-02-13 | 299886001 | 0.612 ppm |
| 2017-02-28 | 975342 | 0.0980 ppm |
| 2017-02-28 | 975339 | 0.1000 ppm |
| 2017-02-28 | 975353 | 0.120 ppm |
| 2017-02-28 | 975335 | 0.130 ppm |
| 2017-02-28 | 975345 | 0.130 ppm |
| 2017-02-28 | 975349 | 0.130 ppm |
| 2017-02-28 | 975332 | 0.790 ppm |
| 2017-03-07 | 303316001 | 0.678 ppm |
| 2017-03-07 | 303316001 | 0.700 ppm |
| 2017-04-12 | 309729001 | 0.871 ppm |
| 2017-04-12 | 309729001 | 0.990 ppm |
| 2017-05-16 | 316757001 | 0.820 ppm |
| 2017-05-16 | 316757001 | 0.846 ppm |
| 2017-06-15 | 322162001 | 0.700 ppm |
| 2017-06-15 | 322162001 | 0.825 ppm |
| 2017-07-17 | 329220001 | 0.750 ppm |
| 2017-07-17 | 329220001 | 0.824 ppm |
| 2017-08-11 | 335116001 | 0.750 ppm |
| 2017-08-11 | 335116001 | 0.851 ppm |
| 2017-09-11 | 341944001 | 0.830 ppm |
| 2017-09-11 | 341944001 | 0.883 ppm |
| 2017-10-12 | 348605001 | 0.840 ppm |
| 2017-10-12 | 348605001 | 0.920 ppm |
| 2017-11-13 | 354074001 | 0.860 ppm |
| 2017-11-13 | 354074001 | 0.942 ppm |
| 2017-12-15 | 359562001 | 0.800 ppm |
| 2017-12-15 | 359562001 | 0.947 ppm |
| 2018-01-16 | 363072001 | 0.890 ppm |
| 2018-01-16 | 363072001 | 0.895 ppm |
| 2018-02-15 | 367278001 | 0.877 ppm |
| 2018-02-15 | 367278001 | 0.900 ppm |
| 2018-03-08 | 370240001 | 0.750 ppm |
| 2018-03-08 | 370240001 | 0.821 ppm |
| 2018-04-12 | 376184001 | 0.880 ppm |
| 2018-04-12 | 376184001 | 0.918 ppm |
| 2018-05-07 | 380536001 | 0.840 ppm |
| 2018-05-07 | 380536001 | 0.930 ppm |
| 2018-06-13 | 388543001 | 0.880 ppm |
| 2018-06-13 | 388543001 | 0.904 ppm |
| 2018-07-12 | 394060001 | 0.911 ppm |
| 2018-07-12 | 394060001 | 0.930 ppm |
| 2018-08-07 | 399599001 | 0.775 ppm |
| 2018-08-07 | 399599001 | 0.810 ppm |
| 2018-09-13 | 407801001 | 0.899 ppm |
| 2018-09-13 | 407801001 | 0.900 ppm |
| 2018-10-15 | 414663001 | 0.909 ppm |
| 2018-10-15 | 414663001 | 0.940 ppm |
| 2018-11-09 | 418978001 | 0.913 ppm |
| 2018-11-09 | 418978001 | 0.950 ppm |
| 2018-12-13 | 424413001 | 0.940 ppm |
| 2018-12-13 | 424413001 | 0.954 ppm |
| 2019-01-08 | 427084001 | 0.957 ppm |
| 2019-01-08 | 427084001 | 0.990 ppm |
| 2019-02-20 | 432533001 | 0.750 ppm |
| 2019-02-20 | 432533001 | 0.818 ppm |
| 2019-03-05 | 434043001 | 0.814 ppm |
| 2019-03-05 | 434043001 | 0.830 ppm |
| 2019-04-03 | 438699001 | 0.775 ppm |
| 2019-04-03 | 438699001 | 0.820 ppm |
| 2019-05-20 | 447529001 | 0.837 ppm |
| 2019-05-20 | 447529001 | 0.870 ppm |
| 2019-06-10 | 450989001 | 0.650 ppm |
| 2019-06-10 | 450989001 | 0.836 ppm |
| 2019-07-15 | 457798001 | 0.785 ppm |
| 2019-07-15 | 457798001 | 0.850 ppm |
| 2019-08-06 | 462205001 | 0.748 ppm |
| 2019-08-06 | 462205001 | 0.750 ppm |
| 2019-09-11 | 469700001 | 0.840 ppm |
| 2019-09-11 | 469700001 | 0.851 ppm |
| 2019-10-17 | 477092001 | 0.760 ppm |
| 2019-10-17 | 477092001 | 0.864 ppm |
| 2019-11-14 | 481598001 | 0.965 ppm |
| 2019-11-14 | 481598001 | 0.990 ppm |
| 2019-12-03 | 484337001 | 0.840 ppm |
| 2019-12-03 | 484337001 | 0.847 ppm |