Fluoride
Watertown 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 | 0.697 ppm | 27 | 27 | 0.586 ppm - 0.801 ppm |
| 2015 | 0.701 ppm | 24 | 24 | 0.580 ppm - 0.950 ppm |
| 2016 | 0.621 ppm | 24 | 24 | 0.441 ppm - 0.800 ppm |
| 2017 | 0.715 ppm | 26 | 26 | 0.580 ppm - 0.850 ppm |
| 2018 | 0.694 ppm | 25 | 25 | 0.190 ppm - 1.50 ppm |
| 2019 | 0.694 ppm | 24 | 24 | 0.410 ppm - 0.810 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 | 115070001 | 0.623 ppm |
| 2014-01-07 | 115070001 | 0.670 ppm |
| 2014-02-04 | 118427001 | 0.671 ppm |
| 2014-02-04 | 118427001 | 0.720 ppm |
| 2014-03-04 | 121843001 | 0.687 ppm |
| 2014-03-04 | 121843001 | 0.720 ppm |
| 2014-04-02 | 125928001 | 0.674 ppm |
| 2014-04-02 | 125928001 | 0.730 ppm |
| 2014-05-05 | 783792 | 0.630 ppm |
| 2014-05-05 | 783786 | 0.720 ppm |
| 2014-05-06 | 131173001 | 0.684 ppm |
| 2014-05-06 | 131173001 | 0.720 ppm |
| 2014-05-08 | 784811 | 0.660 ppm |
| 2014-06-03 | 136753001 | 0.740 ppm |
| 2014-06-03 | 136753001 | 0.795 ppm |
| 2014-07-01 | 142643001 | 0.778 ppm |
| 2014-07-01 | 142643001 | 0.800 ppm |
| 2014-08-05 | 149559001 | 0.586 ppm |
| 2014-08-05 | 149559001 | 0.600 ppm |
| 2014-09-16 | 157921001 | 0.670 ppm |
| 2014-09-16 | 157921001 | 0.674 ppm |
| 2014-10-07 | 162475001 | 0.647 ppm |
| 2014-10-07 | 162475001 | 0.660 ppm |
| 2014-11-04 | 167030001 | 0.750 ppm |
| 2014-11-04 | 167030001 | 0.801 ppm |
| 2014-12-02 | 170754001 | 0.687 ppm |
| 2014-12-02 | 170754001 | 0.720 ppm |
| 2015-01-06 | 174499001 | 0.726 ppm |
| 2015-01-06 | 174499001 | 0.740 ppm |
| 2015-02-10 | 179216001 | 0.700 ppm |
| 2015-02-10 | 179216001 | 0.710 ppm |
| 2015-03-03 | 181868001 | 0.699 ppm |
| 2015-03-03 | 181868001 | 0.790 ppm |
| 2015-04-14 | 188086001 | 0.710 ppm |
| 2015-04-14 | 188086001 | 0.724 ppm |
| 2015-05-05 | 191772001 | 0.674 ppm |
| 2015-05-05 | 191772001 | 0.690 ppm |
| 2015-06-02 | 197460001 | 0.610 ppm |
| 2015-06-02 | 197460001 | 0.646 ppm |
| 2015-07-07 | 204278001 | 0.620 ppm |
| 2015-07-07 | 204278001 | 0.638 ppm |
| 2015-08-04 | 209946001 | 0.721 ppm |
| 2015-08-04 | 209946001 | 0.950 ppm |
| 2015-09-01 | 214951001 | 0.596 ppm |
| 2015-09-01 | 214951001 | 0.820 ppm |
| 2015-10-06 | 222500001 | 0.633 ppm |
| 2015-10-06 | 222500001 | 0.780 ppm |
| 2015-11-03 | 226995001 | 0.580 ppm |
| 2015-11-03 | 226995001 | 0.665 ppm |
| 2015-12-01 | 230772001 | 0.680 ppm |
| 2015-12-01 | 230772001 | 0.730 ppm |
| 2016-01-05 | 234750001 | 0.646 ppm |
| 2016-01-05 | 234750001 | 0.690 ppm |
| 2016-02-01 | 237661001 | 0.646 ppm |
| 2016-02-01 | 237661001 | 0.750 ppm |
| 2016-03-01 | 241853001 | 0.670 ppm |
| 2016-03-01 | 241853001 | 0.711 ppm |
| 2016-04-05 | 247308001 | 0.761 ppm |
| 2016-04-05 | 247308001 | 0.800 ppm |
| 2016-05-03 | 252004001 | 0.587 ppm |
| 2016-05-03 | 252004001 | 0.640 ppm |
| 2016-06-07 | 259029001 | 0.670 ppm |
| 2016-06-07 | 259029001 | 0.688 ppm |
| 2016-07-05 | 264244001 | 0.441 ppm |
| 2016-07-05 | 264244001 | 0.480 ppm |
| 2016-08-02 | 270075001 | 0.521 ppm |
| 2016-08-02 | 270075001 | 0.530 ppm |
| 2016-09-06 | 275802001 | 0.627 ppm |
| 2016-09-06 | 275802001 | 0.650 ppm |
| 2016-10-03 | 281906001 | 0.590 ppm |
| 2016-10-03 | 281906001 | 0.608 ppm |
| 2016-11-01 | 286961001 | 0.570 ppm |
| 2016-11-01 | 286961001 | 0.579 ppm |
| 2016-12-06 | 291843001 | 0.510 ppm |
| 2016-12-06 | 291843001 | 0.530 ppm |
| 2017-01-03 | 294900001 | 0.580 ppm |
| 2017-01-03 | 294900001 | 0.610 ppm |
| 2017-02-07 | 299235001 | 0.671 ppm |
| 2017-02-07 | 299235001 | 0.680 ppm |
| 2017-03-07 | 303179001 | 0.747 ppm |
| 2017-03-07 | 303179001 | 0.760 ppm |
| 2017-04-04 | 308016001 | 0.597 ppm |
| 2017-04-04 | 308016001 | 0.620 ppm |
| 2017-05-02 | 313442001 | 0.674 ppm |
| 2017-05-02 | 313442001 | 0.730 ppm |
| 2017-05-03 | 986657 | 0.670 ppm |
| 2017-05-03 | 986653 | 0.760 ppm |
| 2017-06-06 | 320316001 | 0.826 ppm |
| 2017-06-06 | 320316001 | 0.830 ppm |
| 2017-07-11 | 327935001 | 0.761 ppm |
| 2017-07-11 | 327935001 | 0.850 ppm |
| 2017-08-01 | 332690001 | 0.650 ppm |
| 2017-08-01 | 332690001 | 0.666 ppm |
| 2017-09-05 | 340102001 | 0.660 ppm |
| 2017-09-05 | 340102001 | 0.705 ppm |
| 2017-10-03 | 346755001 | 0.663 ppm |
| 2017-10-03 | 346755001 | 0.670 ppm |
| 2017-11-07 | 353265001 | 0.800 ppm |
| 2017-11-07 | 353265001 | 0.830 ppm |
| 2017-12-05 | 357894001 | 0.770 ppm |
| 2017-12-05 | 357894001 | 0.819 ppm |
| 2018-01-09 | 362341001 | 0.547 ppm |
| 2018-01-09 | 362341001 | 0.590 ppm |
| 2018-02-06 | 365877001 | 0.570 ppm |
| 2018-02-06 | 365877001 | 0.598 ppm |
| 2018-02-12 | 1040465 | 1.50 ppm |
| 2018-03-06 | 369782001 | 0.690 ppm |
| 2018-03-06 | 369782001 | 0.819 ppm |
| 2018-04-03 | 374462001 | 0.580 ppm |
| 2018-04-03 | 374462001 | 0.654 ppm |
| 2018-05-08 | 381012001 | 0.190 ppm |
| 2018-05-08 | 381012001 | 0.207 ppm |
| 2018-06-05 | 386678001 | 0.630 ppm |
| 2018-06-05 | 386678001 | 0.737 ppm |
| 2018-07-10 | 393613001 | 0.780 ppm |
| 2018-07-10 | 393613001 | 0.886 ppm |
| 2018-08-07 | 399587001 | 0.770 ppm |
| 2018-08-07 | 399587001 | 0.774 ppm |
| 2018-09-04 | 405119001 | 0.720 ppm |
| 2018-09-04 | 405119001 | 0.732 ppm |
| 2018-10-09 | 413572001 | 0.694 ppm |
| 2018-10-09 | 413572001 | 0.730 ppm |
| 2018-11-06 | 418559001 | 0.664 ppm |
| 2018-11-06 | 418559001 | 0.700 ppm |
| 2018-12-04 | 422723001 | 0.772 ppm |
| 2018-12-04 | 422723001 | 0.810 ppm |
| 2019-01-08 | 427067001 | 0.730 ppm |
| 2019-01-08 | 427067001 | 0.810 ppm |
| 2019-02-05 | 430394001 | 0.757 ppm |
| 2019-02-05 | 430394001 | 0.810 ppm |
| 2019-03-05 | 434066001 | 0.680 ppm |
| 2019-03-05 | 434066001 | 0.699 ppm |
| 2019-04-16 | 441083001 | 0.410 ppm |
| 2019-04-16 | 441083001 | 0.423 ppm |
| 2019-05-07 | 444778001 | 0.560 ppm |
| 2019-05-07 | 444778001 | 0.573 ppm |
| 2019-06-04 | 450003001 | 0.690 ppm |
| 2019-06-04 | 450003001 | 0.727 ppm |
| 2019-07-09 | 456689001 | 0.680 ppm |
| 2019-07-09 | 456689001 | 0.800 ppm |
| 2019-08-06 | 462200001 | 0.690 ppm |
| 2019-08-06 | 462200001 | 0.706 ppm |
| 2019-09-03 | 467523001 | 0.705 ppm |
| 2019-09-03 | 467523001 | 0.770 ppm |
| 2019-10-01 | 474004001 | 0.729 ppm |
| 2019-10-01 | 474004001 | 0.730 ppm |
| 2019-11-05 | 480021001 | 0.740 ppm |
| 2019-11-05 | 480021001 | 0.742 ppm |
| 2019-12-03 | 484322001 | 0.717 ppm |
| 2019-12-03 | 484322001 | 0.770 ppm |