Fluoride
Hartford 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 |
|---|---|---|---|---|
| 2013 | N/A | 0 | 0 | N/A |
| 2014 | 0.612 ppm | 29 | 29 | 0.0670 ppm - 0.926 ppm |
| 2015 | 0.741 ppm | 24 | 24 | 0.680 ppm - 0.876 ppm |
| 2016 | 0.706 ppm | 24 | 24 | 0.644 ppm - 0.850 ppm |
| 2017 | 0.636 ppm | 29 | 29 | 0.0880 ppm - 0.873 ppm |
| 2018 | 0.745 ppm | 24 | 24 | 0.464 ppm - 0.926 ppm |
| 2019 | 0.732 ppm | 24 | 24 | 0.627 ppm - 0.872 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 |
|---|---|---|
| 2014-01-21 | 116893001 | 0.659 ppm |
| 2014-01-21 | 116893001 | 0.671 ppm |
| 2014-02-06 | 118826001 | 0.503 ppm |
| 2014-02-06 | 118826001 | 0.690 ppm |
| 2014-03-04 | 121844001 | 0.747 ppm |
| 2014-03-04 | 121844001 | 0.790 ppm |
| 2014-03-18 | 775377 | 0.0670 ppm |
| 2014-03-18 | 775380 | 0.0700 ppm |
| 2014-03-18 | 775371 | 0.0730 ppm |
| 2014-03-18 | 775374 | 0.0800 ppm |
| 2014-03-18 | 775383 | 0.0810 ppm |
| 2014-04-10 | 127286001 | 0.673 ppm |
| 2014-04-10 | 127286001 | 0.705 ppm |
| 2014-05-07 | 131331001 | 0.646 ppm |
| 2014-05-07 | 131331001 | 0.708 ppm |
| 2014-06-03 | 136804001 | 0.691 ppm |
| 2014-06-03 | 136804001 | 0.710 ppm |
| 2014-07-22 | 146956001 | 0.830 ppm |
| 2014-07-22 | 146956001 | 0.846 ppm |
| 2014-08-05 | 149736001 | 0.731 ppm |
| 2014-08-05 | 149736001 | 0.736 ppm |
| 2014-09-10 | 156612001 | 0.661 ppm |
| 2014-09-10 | 156612001 | 0.720 ppm |
| 2014-10-08 | 162894001 | 0.792 ppm |
| 2014-10-08 | 162894001 | 0.926 ppm |
| 2014-11-12 | 168248001 | 0.715 ppm |
| 2014-11-12 | 168248001 | 0.745 ppm |
| 2014-12-02 | 170751001 | 0.729 ppm |
| 2014-12-02 | 170751001 | 0.751 ppm |
| 2015-01-06 | 174649001 | 0.756 ppm |
| 2015-01-06 | 174649001 | 0.876 ppm |
| 2015-02-10 | 179217001 | 0.732 ppm |
| 2015-02-10 | 179217001 | 0.778 ppm |
| 2015-03-10 | 183020001 | 0.680 ppm |
| 2015-03-10 | 183020001 | 0.683 ppm |
| 2015-04-15 | 188348001 | 0.720 ppm |
| 2015-04-15 | 188348001 | 0.766 ppm |
| 2015-05-07 | 192161001 | 0.720 ppm |
| 2015-05-07 | 192161001 | 0.731 ppm |
| 2015-06-09 | 198560001 | 0.755 ppm |
| 2015-06-09 | 198560001 | 0.765 ppm |
| 2015-07-08 | 204597001 | 0.680 ppm |
| 2015-07-08 | 204597001 | 0.742 ppm |
| 2015-08-05 | 210216001 | 0.724 ppm |
| 2015-08-05 | 210216001 | 0.726 ppm |
| 2015-09-09 | 216455001 | 0.712 ppm |
| 2015-09-09 | 216455001 | 0.724 ppm |
| 2015-10-07 | 222636001 | 0.791 ppm |
| 2015-10-07 | 222636001 | 0.837 ppm |
| 2015-11-10 | 228159001 | 0.712 ppm |
| 2015-11-10 | 228159001 | 0.745 ppm |
| 2015-12-01 | 230771001 | 0.710 ppm |
| 2015-12-01 | 230771001 | 0.726 ppm |
| 2016-01-06 | 234925001 | 0.692 ppm |
| 2016-01-06 | 234925001 | 0.713 ppm |
| 2016-02-10 | 239479001 | 0.671 ppm |
| 2016-02-10 | 239479001 | 0.744 ppm |
| 2016-03-09 | 243498001 | 0.706 ppm |
| 2016-03-09 | 243498001 | 0.729 ppm |
| 2016-04-19 | 249759001 | 0.701 ppm |
| 2016-04-19 | 249759001 | 0.769 ppm |
| 2016-05-10 | 253882001 | 0.711 ppm |
| 2016-05-10 | 253882001 | 0.850 ppm |
| 2016-06-07 | 259048001 | 0.653 ppm |
| 2016-06-07 | 259048001 | 0.675 ppm |
| 2016-07-12 | 265915001 | 0.674 ppm |
| 2016-07-12 | 265915001 | 0.683 ppm |
| 2016-08-09 | 271235001 | 0.712 ppm |
| 2016-08-09 | 271235001 | 0.714 ppm |
| 2016-09-07 | 276307001 | 0.644 ppm |
| 2016-09-07 | 276307001 | 0.681 ppm |
| 2016-10-11 | 283578001 | 0.689 ppm |
| 2016-10-11 | 283578001 | 0.704 ppm |
| 2016-11-08 | 288229001 | 0.703 ppm |
| 2016-11-08 | 288229001 | 0.718 ppm |
| 2016-12-06 | 291844001 | 0.698 ppm |
| 2016-12-06 | 291844001 | 0.702 ppm |
| 2017-01-04 | 295092001 | 0.686 ppm |
| 2017-01-04 | 295092001 | 0.714 ppm |
| 2017-02-07 | 299248001 | 0.692 ppm |
| 2017-02-07 | 299248001 | 0.702 ppm |
| 2017-03-09 | 303464001 | 0.714 ppm |
| 2017-03-09 | 303464001 | 0.774 ppm |
| 2017-03-21 | 978881 | 0.0880 ppm |
| 2017-03-21 | 978875 | 0.0960 ppm |
| 2017-03-21 | 978869 | 0.0970 ppm |
| 2017-03-21 | 978872 | 0.110 ppm |
| 2017-03-21 | 978878 | 0.110 ppm |
| 2017-04-05 | 308273001 | 0.590 ppm |
| 2017-04-05 | 308273001 | 0.622 ppm |
| 2017-05-16 | 316413001 | 0.761 ppm |
| 2017-05-16 | 316413001 | 0.803 ppm |
| 2017-06-14 | 322055001 | 0.734 ppm |
| 2017-06-14 | 322055001 | 0.786 ppm |
| 2017-07-12 | 328278001 | 0.803 ppm |
| 2017-07-12 | 328278001 | 0.848 ppm |
| 2017-08-08 | 334534001 | 0.615 ppm |
| 2017-08-08 | 334534001 | 0.661 ppm |
| 2017-09-11 | 341367001 | 0.786 ppm |
| 2017-09-11 | 341367001 | 0.871 ppm |
| 2017-10-11 | 348548001 | 0.764 ppm |
| 2017-10-11 | 348548001 | 0.808 ppm |
| 2017-11-07 | 353257001 | 0.734 ppm |
| 2017-11-07 | 353257001 | 0.856 ppm |
| 2017-12-05 | 357892001 | 0.734 ppm |
| 2017-12-05 | 357892001 | 0.873 ppm |
| 2018-01-10 | 362518001 | 0.779 ppm |
| 2018-01-10 | 362518001 | 0.781 ppm |
| 2018-02-07 | 366088001 | 0.778 ppm |
| 2018-02-07 | 366088001 | 0.797 ppm |
| 2018-03-07 | 370244001 | 0.613 ppm |
| 2018-03-07 | 370244001 | 0.677 ppm |
| 2018-04-04 | 374643001 | 0.464 ppm |
| 2018-04-04 | 374643001 | 0.470 ppm |
| 2018-05-03 | 379838001 | 0.770 ppm |
| 2018-05-03 | 379838001 | 0.804 ppm |
| 2018-06-14 | 388799001 | 0.851 ppm |
| 2018-06-14 | 388799001 | 0.917 ppm |
| 2018-07-11 | 393923001 | 0.813 ppm |
| 2018-07-11 | 393923001 | 0.926 ppm |
| 2018-08-07 | 399590001 | 0.906 ppm |
| 2018-08-07 | 399590001 | 0.916 ppm |
| 2018-09-05 | 405402001 | 0.767 ppm |
| 2018-09-05 | 405402001 | 0.779 ppm |
| 2018-10-04 | 412694001 | 0.581 ppm |
| 2018-10-04 | 412694001 | 0.605 ppm |
| 2018-11-06 | 418558001 | 0.701 ppm |
| 2018-11-06 | 418558001 | 0.788 ppm |
| 2018-12-04 | 422693001 | 0.691 ppm |
| 2018-12-04 | 422693001 | 0.717 ppm |
| 2019-01-09 | 427267001 | 0.691 ppm |
| 2019-01-09 | 427267001 | 0.714 ppm |
| 2019-02-05 | 430416001 | 0.688 ppm |
| 2019-02-05 | 430416001 | 0.760 ppm |
| 2019-03-05 | 434055001 | 0.693 ppm |
| 2019-03-05 | 434055001 | 0.761 ppm |
| 2019-04-09 | 439826001 | 0.627 ppm |
| 2019-04-09 | 439826001 | 0.740 ppm |
| 2019-05-08 | 445114001 | 0.731 ppm |
| 2019-05-08 | 445114001 | 0.872 ppm |
| 2019-06-10 | 450984001 | 0.754 ppm |
| 2019-06-10 | 450984001 | 0.782 ppm |
| 2019-07-02 | 455441001 | 0.745 ppm |
| 2019-07-02 | 455441001 | 0.757 ppm |
| 2019-08-12 | 463144001 | 0.742 ppm |
| 2019-08-12 | 463144001 | 0.808 ppm |
| 2019-09-10 | 469390001 | 0.696 ppm |
| 2019-09-10 | 469390001 | 0.708 ppm |
| 2019-10-08 | 475460001 | 0.680 ppm |
| 2019-10-08 | 475460001 | 0.703 ppm |
| 2019-11-14 | 481596001 | 0.627 ppm |
| 2019-11-14 | 481596001 | 0.735 ppm |
| 2019-12-04 | 484599001 | 0.741 ppm |
| 2019-12-04 | 484599001 | 0.805 ppm |