Fluoride
North Shore Water Commission
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 | 0.815 ppm | 25 | 25 | 0.680 ppm - 1.38 ppm |
| 2015 | 0.752 ppm | 25 | 25 | 0.690 ppm - 0.905 ppm |
| 2016 | 0.793 ppm | 25 | 25 | 0.713 ppm - 0.930 ppm |
| 2017 | 0.749 ppm | 25 | 25 | 0.688 ppm - 0.800 ppm |
| 2018 | 0.738 ppm | 25 | 25 | 0.636 ppm - 0.840 ppm |
| 2019 | 0.720 ppm | 25 | 25 | 0.590 ppm - 0.790 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 |
|---|---|---|
| 2014-01-14 | 116474001 | 0.747 ppm |
| 2014-01-14 | 116474001 | 0.760 ppm |
| 2014-02-17 | 120426001 | 0.803 ppm |
| 2014-02-17 | 120426001 | 0.940 ppm |
| 2014-03-06 | 122213001 | 0.733 ppm |
| 2014-03-06 | 122213001 | 0.750 ppm |
| 2014-04-15 | 780525 | 0.680 ppm |
| 2014-04-15 | 128002001 | 0.703 ppm |
| 2014-04-15 | 128002001 | 0.750 ppm |
| 2014-05-14 | 133085001 | 0.739 ppm |
| 2014-05-14 | 133085001 | 0.770 ppm |
| 2014-06-03 | 137217001 | 0.749 ppm |
| 2014-06-03 | 137217001 | 0.780 ppm |
| 2014-07-16 | 146139001 | 0.770 ppm |
| 2014-07-16 | 146139001 | 0.786 ppm |
| 2014-08-11 | 151086001 | 0.813 ppm |
| 2014-08-11 | 151086001 | 0.870 ppm |
| 2014-09-17 | 158596001 | 0.706 ppm |
| 2014-09-17 | 158596001 | 0.730 ppm |
| 2014-10-01 | 161417001 | 0.738 ppm |
| 2014-10-01 | 161417001 | 0.750 ppm |
| 2014-11-17 | 169077001 | 1.37 ppm |
| 2014-11-17 | 169077001 | 1.38 ppm |
| 2014-12-02 | 171004001 | 0.773 ppm |
| 2014-12-02 | 171004001 | 0.790 ppm |
| 2015-01-22 | 176930001 | 0.693 ppm |
| 2015-01-22 | 176930001 | 0.700 ppm |
| 2015-02-05 | 178607001 | 0.740 ppm |
| 2015-02-05 | 178607001 | 0.758 ppm |
| 2015-03-03 | 182165001 | 0.740 ppm |
| 2015-03-03 | 845996 | 0.760 ppm |
| 2015-03-03 | 182165001 | 0.785 ppm |
| 2015-04-15 | 188451001 | 0.750 ppm |
| 2015-04-15 | 188451001 | 0.752 ppm |
| 2015-05-07 | 192191001 | 0.718 ppm |
| 2015-05-07 | 192191001 | 0.734 ppm |
| 2015-06-03 | 197902001 | 0.710 ppm |
| 2015-06-03 | 197902001 | 0.783 ppm |
| 2015-07-09 | 204785001 | 0.718 ppm |
| 2015-07-09 | 204785001 | 0.750 ppm |
| 2015-08-18 | 213135001 | 0.720 ppm |
| 2015-08-18 | 213135001 | 0.742 ppm |
| 2015-09-02 | 215587001 | 0.723 ppm |
| 2015-09-02 | 215587001 | 0.744 ppm |
| 2015-10-19 | 224611001 | 0.690 ppm |
| 2015-10-19 | 224611001 | 0.745 ppm |
| 2015-11-03 | 227304001 | 0.830 ppm |
| 2015-11-03 | 227304001 | 0.905 ppm |
| 2015-12-02 | 231036001 | 0.790 ppm |
| 2015-12-02 | 231036001 | 0.822 ppm |
| 2016-01-25 | 237252001 | 0.780 ppm |
| 2016-01-25 | 237252001 | 0.801 ppm |
| 2016-02-17 | 240495001 | 0.760 ppm |
| 2016-02-17 | 240495001 | 0.809 ppm |
| 2016-03-14 | 244443001 | 0.870 ppm |
| 2016-03-14 | 244443001 | 0.894 ppm |
| 2016-03-14 | 909875 | 0.930 ppm |
| 2016-04-11 | 248703001 | 0.790 ppm |
| 2016-04-11 | 248703001 | 0.798 ppm |
| 2016-05-09 | 254055001 | 0.790 ppm |
| 2016-05-09 | 254055001 | 0.795 ppm |
| 2016-06-20 | 262033001 | 0.760 ppm |
| 2016-06-20 | 262033001 | 0.766 ppm |
| 2016-07-12 | 266199001 | 0.840 ppm |
| 2016-07-12 | 266199001 | 0.850 ppm |
| 2016-08-17 | 273059001 | 0.713 ppm |
| 2016-08-17 | 273059001 | 0.720 ppm |
| 2016-09-19 | 279298001 | 0.753 ppm |
| 2016-09-19 | 279298001 | 0.760 ppm |
| 2016-10-18 | 285003001 | 0.782 ppm |
| 2016-10-18 | 285003001 | 0.830 ppm |
| 2016-11-14 | 289427001 | 0.720 ppm |
| 2016-11-14 | 289427001 | 0.744 ppm |
| 2016-12-13 | 293381001 | 0.770 ppm |
| 2016-12-13 | 293381001 | 0.790 ppm |
| 2017-01-17 | 296798001 | 0.770 ppm |
| 2017-01-17 | 296798001 | 0.793 ppm |
| 2017-02-13 | 300267001 | 0.718 ppm |
| 2017-02-13 | 300267001 | 0.732 ppm |
| 2017-03-15 | 304703001 | 0.750 ppm |
| 2017-03-15 | 304703001 | 0.757 ppm |
| 2017-04-18 | 311032001 | 0.740 ppm |
| 2017-04-18 | 311032001 | 0.748 ppm |
| 2017-04-18 | 983835 | 0.780 ppm |
| 2017-05-17 | 316859001 | 0.728 ppm |
| 2017-05-17 | 316859001 | 0.750 ppm |
| 2017-06-05 | 320269001 | 0.753 ppm |
| 2017-06-05 | 320269001 | 0.790 ppm |
| 2017-07-18 | 329911001 | 0.709 ppm |
| 2017-07-18 | 329911001 | 0.750 ppm |
| 2017-08-22 | 338127001 | 0.688 ppm |
| 2017-08-22 | 338127001 | 0.750 ppm |
| 2017-09-19 | 344072001 | 0.697 ppm |
| 2017-09-19 | 344072001 | 0.790 ppm |
| 2017-10-18 | 349996001 | 0.739 ppm |
| 2017-10-18 | 349996001 | 0.760 ppm |
| 2017-11-14 | 354939001 | 0.697 ppm |
| 2017-11-14 | 354939001 | 0.760 ppm |
| 2017-12-12 | 359275001 | 0.767 ppm |
| 2017-12-12 | 359275001 | 0.800 ppm |
| 2018-01-16 | 363376001 | 0.636 ppm |
| 2018-01-16 | 363376001 | 0.660 ppm |
| 2018-02-20 | 368130001 | 0.673 ppm |
| 2018-02-20 | 368130001 | 0.700 ppm |
| 2018-03-20 | 1046101 | 0.700 ppm |
| 2018-03-20 | 372478001 | 0.720 ppm |
| 2018-03-20 | 372478001 | 0.730 ppm |
| 2018-04-18 | 377315001 | 0.700 ppm |
| 2018-04-18 | 377315001 | 0.728 ppm |
| 2018-05-15 | 383208001 | 0.710 ppm |
| 2018-05-15 | 383208001 | 0.732 ppm |
| 2018-06-04 | 386683001 | 0.793 ppm |
| 2018-06-04 | 386683001 | 0.840 ppm |
| 2018-07-17 | 395574001 | 0.790 ppm |
| 2018-07-17 | 395574001 | 0.834 ppm |
| 2018-08-23 | 403238001 | 0.740 ppm |
| 2018-08-23 | 403238001 | 0.770 ppm |
| 2018-09-04 | 405512001 | 0.760 ppm |
| 2018-09-04 | 405512001 | 0.794 ppm |
| 2018-10-09 | 413915001 | 0.700 ppm |
| 2018-10-09 | 413915001 | 0.704 ppm |
| 2018-11-13 | 420345001 | 0.740 ppm |
| 2018-11-13 | 420345001 | 0.764 ppm |
| 2018-12-04 | 423025001 | 0.737 ppm |
| 2018-12-04 | 423025001 | 0.800 ppm |
| 2019-01-15 | 428307001 | 0.768 ppm |
| 2019-01-15 | 428307001 | 0.790 ppm |
| 2019-02-19 | 1105889 | 0.590 ppm |
| 2019-02-19 | 432674001 | 0.650 ppm |
| 2019-02-19 | 432674001 | 0.682 ppm |
| 2019-03-19 | 436604001 | 0.746 ppm |
| 2019-03-19 | 436604001 | 0.780 ppm |
| 2019-04-16 | 441171001 | 0.740 ppm |
| 2019-04-16 | 441171001 | 0.754 ppm |
| 2019-05-15 | 446667001 | 0.680 ppm |
| 2019-05-15 | 446667001 | 0.736 ppm |
| 2019-06-04 | 450211001 | 0.720 ppm |
| 2019-06-04 | 450211001 | 0.739 ppm |
| 2019-07-15 | 458606001 | 0.755 ppm |
| 2019-07-15 | 458606001 | 0.790 ppm |
| 2019-08-14 | 464190001 | 0.647 ppm |
| 2019-08-14 | 464190001 | 0.700 ppm |
| 2019-09-04 | 468033001 | 0.661 ppm |
| 2019-09-04 | 468033001 | 0.710 ppm |
| 2019-10-15 | 477094001 | 0.754 ppm |
| 2019-10-15 | 477094001 | 0.760 ppm |
| 2019-11-06 | 480518001 | 0.702 ppm |
| 2019-11-06 | 480518001 | 0.740 ppm |
| 2019-12-03 | 484572001 | 0.695 ppm |
| 2019-12-03 | 484572001 | 0.720 ppm |