Fluoride
City of San Juan Capistrano
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.
Testing results - average by year
Year | Average result | Samples taken | Detections | Range of results |
---|---|---|---|---|
2014 | 0.654 ppm | 8 | 8 | 0.240 ppm - 0.890 ppm |
2015 | 0.234 ppm | 11 | 11 | 0.180 ppm - 0.250 ppm |
2016 | 0.244 ppm | 9 | 9 | 0.240 ppm - 0.250 ppm |
2017 | 0.256 ppm | 10 | 10 | 0.240 ppm - 0.280 ppm |
2018 | 0.248 ppm | 12 | 12 | 0.230 ppm - 0.270 ppm |
2019 | 0.269 ppm | 4 | 4 | 0.256 ppm - 0.287 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 |
---|---|---|
2014-01-22 | 9590-010-1235 | 0.870 ppm |
2014-02-19 | 9590-010-0810 | 0.840 ppm |
2014-03-18 | 9590-010-0919 | 0.890 ppm |
2014-04-22 | 9590-010-0814 | 0.860 ppm |
2014-05-20 | 9590-010-0854 | 0.840 ppm |
2014-06-17 | 9590-010-0936 | 0.420 ppm |
2014-07-22 | 9590-010-0800 | 0.270 ppm |
2014-12-23 | 9590-010-1508 | 0.240 ppm |
2015-01-22 | 9590-010-0930 | 0.240 ppm |
2015-02-10 | 9590-010-1111 | 0.240 ppm |
2015-03-03 | 9590-010-0905 | 0.230 ppm |
2015-04-21 | 9590-010-0750 | 0.180 ppm |
2015-05-19 | 9590-010-0808 | 0.240 ppm |
2015-08-12 | 9590-010-1130 | 0.240 ppm |
2015-08-24 | 9590-010-0911 | 0.250 ppm |
2015-09-22 | 9590-010-0804 | 0.230 ppm |
2015-10-27 | 9590-010-0808 | 0.230 ppm |
2015-11-17 | 9590-010-0755 | 0.250 ppm |
2015-12-28 | 9590-010-0815 | 0.240 ppm |
2016-01-18 | 9590-010-1325 | 0.250 ppm |
2016-02-01 | 9590-010-1208 | 0.240 ppm |
2016-02-29 | 9590-010-0809 | 0.240 ppm |
2016-03-29 | 9590-010-0744 | 0.240 ppm |
2016-04-19 | 9590-010-0835 | 0.240 ppm |
2016-05-16 | 9590-010-0734 | 0.240 ppm |
2016-06-21 | 9590-010-1027 | 0.250 ppm |
2016-07-18 | 9590-010-0950 | 0.250 ppm |
2016-08-15 | 9590-010-1027 | 0.250 ppm |
2017-02-08 | 9590-010-0815 | 0.250 ppm |
2017-03-08 | 9590-010-0747 | 0.260 ppm |
2017-04-05 | 9590-010-0735 | 0.280 ppm |
2017-05-03 | 9590-010-0907 | 0.260 ppm |
2017-07-07 | 9590-010-0808 | 0.260 ppm |
2017-08-10 | 9590-010-0730 | 0.250 ppm |
2017-09-19 | 9590-010-1236 | 0.250 ppm |
2017-10-04 | 9590-010-0815 | 0.250 ppm |
2017-11-08 | 9590-010-0815 | 0.260 ppm |
2017-12-07 | 9590-010-0821 | 0.240 ppm |
2018-01-22 | 9590-010-1158 | 0.270 ppm |
2018-02-13 | 9590-010-1340 | 0.240 ppm |
2018-03-12 | 9590-010-1310 | 0.250 ppm |
2018-04-19 | 9590-010-1515 | 0.250 ppm |
2018-05-10 | 9590-010-1225 | 0.240 ppm |
2018-06-06 | 9590-010-1200 | 0.230 ppm |
2018-07-30 | 9590-010-1425 | 0.260 ppm |
2018-08-15 | 9590-010-1240 | 0.270 ppm |
2018-09-06 | 9590-010-1325 | 0.230 ppm |
2018-10-22 | 9590-010-1210 | 0.250 ppm |
2018-11-07 | 9590-010-1250 | 0.240 ppm |
2018-12-19 | 9590-010-0807 | 0.240 ppm |
2019-03-13 | 4792-010-1005 | 0.287 ppm |
2019-08-13 | 4792-010-1100 | 0.263 ppm |
2019-09-10 | 4792-010-1020 | 0.268 ppm |
2019-11-19 | 4792-010-1150 | 0.256 ppm |