Fluoride
Alameda County Water District
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 | 0.932 ppm | 17 | 17 | 0.850 ppm - 1.01 ppm |
| 2015 | 0.875 ppm | 13 | 13 | 0.670 ppm - 0.950 ppm |
| 2016 | 0.871 ppm | 16 | 16 | 0.630 ppm - 1.000 ppm |
| 2017 | 0.808 ppm | 16 | 16 | 0.700 ppm - 0.921 ppm |
| 2018 | 0.769 ppm | 16 | 16 | 0.700 ppm - 0.854 ppm |
| 2019 | 0.743 ppm | 16 | 16 | 0.660 ppm - 0.820 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 |
|---|---|---|
| 2014-03-04 | 5401-053-0955 | 0.920 ppm |
| 2014-03-04 | 5401-038-0925 | 0.920 ppm |
| 2014-03-04 | 5401-041-0930 | 0.900 ppm |
| 2014-03-04 | 5401-040-0845 | 1.01 ppm |
| 2014-04-29 | 5401-053-1025 | 0.920 ppm |
| 2014-04-29 | 5401-041-1000 | 1.000 ppm |
| 2014-04-29 | 5401-038-1005 | 0.920 ppm |
| 2014-05-27 | 5401-015-1005 | 0.980 ppm |
| 2014-05-27 | 5401-040-1050 | 0.880 ppm |
| 2014-07-21 | 5401-041-0955 | 0.920 ppm |
| 2014-07-21 | 5401-038-0955 | 0.920 ppm |
| 2014-07-22 | 5401-053-0905 | 0.970 ppm |
| 2014-07-22 | 5401-040-0925 | 0.970 ppm |
| 2014-10-14 | 5401-053-1145 | 0.990 ppm |
| 2014-10-14 | 5401-038-1000 | 0.850 ppm |
| 2014-10-14 | 5401-040-0900 | 0.850 ppm |
| 2014-10-14 | 5401-041-1025 | 0.920 ppm |
| 2015-04-21 | 5401-038-0945 | 0.920 ppm |
| 2015-04-21 | 5401-053-1010 | 0.910 ppm |
| 2015-04-21 | 5401-041-0935 | 0.920 ppm |
| 2015-04-21 | 5401-040-0910 | 0.900 ppm |
| 2015-06-09 | 5401-015-1120 | 0.910 ppm |
| 2015-07-06 | 5401-040-1105 | 0.890 ppm |
| 2015-07-06 | 5401-038-1000 | 0.840 ppm |
| 2015-07-06 | 5401-041-0921 | 0.670 ppm |
| 2015-07-21 | 5401-053-0905 | 0.950 ppm |
| 2015-10-20 | 5401-040-0940 | 0.870 ppm |
| 2015-10-20 | 5401-038-1035 | 0.950 ppm |
| 2015-10-20 | 5401-053-1115 | 0.950 ppm |
| 2015-10-20 | 5401-041-1025 | 0.690 ppm |
| 2016-01-19 | 5401-040-1035 | 0.920 ppm |
| 2016-01-19 | 5401-038-0855 | 0.890 ppm |
| 2016-01-19 | 5401-053-0935 | 0.950 ppm |
| 2016-01-19 | 5401-041-0910 | 0.670 ppm |
| 2016-04-26 | 5401-038-1035 | 0.890 ppm |
| 2016-04-26 | 5401-041-1025 | 0.700 ppm |
| 2016-04-26 | 5401-040-0945 | 0.830 ppm |
| 2016-05-10 | 5401-053-0915 | 0.970 ppm |
| 2016-07-11 | 5401-038-0850 | 0.980 ppm |
| 2016-07-11 | 5401-041-0820 | 0.660 ppm |
| 2016-07-19 | 5401-040-0825 | 0.970 ppm |
| 2016-07-19 | 5401-053-0955 | 0.950 ppm |
| 2016-10-04 | 5401-040-0825 | 0.950 ppm |
| 2016-10-04 | 5401-041-0855 | 0.630 ppm |
| 2016-10-04 | 5401-053-0925 | 1.000 ppm |
| 2016-10-04 | 5401-038-0905 | 0.970 ppm |
| 2017-01-17 | 5401-040-0937 | 0.760 ppm |
| 2017-01-17 | 5401-041-0925 | 0.700 ppm |
| 2017-01-17 | 5401-038-0925 | 0.860 ppm |
| 2017-01-17 | 5401-053-1025 | 0.870 ppm |
| 2017-04-18 | 5401-038-0925 | 0.809 ppm |
| 2017-04-18 | 5401-040-0820 | 0.845 ppm |
| 2017-04-18 | 5401-053-0948 | 0.832 ppm |
| 2017-04-18 | 5401-041-0910 | 0.706 ppm |
| 2017-07-17 | 5401-038-1030 | 0.826 ppm |
| 2017-07-17 | 5401-041-1005 | 0.735 ppm |
| 2017-07-25 | 5401-040-0915 | 0.921 ppm |
| 2017-07-25 | 5401-053-1032 | 0.873 ppm |
| 2017-10-03 | 5401-038-0915 | 0.828 ppm |
| 2017-10-03 | 5401-053-0958 | 0.868 ppm |
| 2017-10-03 | 5401-040-0857 | 0.777 ppm |
| 2017-10-03 | 5401-041-0925 | 0.721 ppm |
| 2018-01-16 | 5401-040-0920 | 0.724 ppm |
| 2018-01-16 | 5401-038-1110 | 0.854 ppm |
| 2018-01-16 | 5401-053-1050 | 0.792 ppm |
| 2018-01-16 | 5401-041-1025 | 0.712 ppm |
| 2018-04-17 | 5401-040-0835 | 0.834 ppm |
| 2018-04-17 | 5401-038-0926 | 0.808 ppm |
| 2018-04-17 | 5401-053-1003 | 0.854 ppm |
| 2018-04-17 | 5401-041-0939 | 0.732 ppm |
| 2018-07-11 | 5401-038-0726 | 0.780 ppm |
| 2018-07-11 | 5401-041-0755 | 0.730 ppm |
| 2018-07-17 | 5401-040-0850 | 0.770 ppm |
| 2018-07-17 | 5401-053-0845 | 0.750 ppm |
| 2018-10-16 | 5401-041-1005 | 0.700 ppm |
| 2018-10-16 | 5401-038-0950 | 0.750 ppm |
| 2018-10-16 | 5401-053-1035 | 0.790 ppm |
| 2018-10-16 | 5401-040-0820 | 0.730 ppm |
| 2019-02-05 | 5401-053-1000 | 0.780 ppm |
| 2019-02-05 | 5401-038-0940 | 0.740 ppm |
| 2019-02-05 | 5401-041-0930 | 0.660 ppm |
| 2019-02-05 | 5401-040-0820 | 0.720 ppm |
| 2019-05-13 | 5401-053-0955 | 0.810 ppm |
| 2019-05-14 | 5401-040-0815 | 0.710 ppm |
| 2019-05-14 | 5401-038-0900 | 0.710 ppm |
| 2019-05-14 | 5401-041-0915 | 0.680 ppm |
| 2019-07-16 | 5401-053-1030 | 0.820 ppm |
| 2019-07-16 | 5401-041-1000 | 0.700 ppm |
| 2019-07-16 | 5401-038-0935 | 0.750 ppm |
| 2019-07-16 | 5401-040-0755 | 0.740 ppm |
| 2019-10-15 | 5401-053-1000 | 0.790 ppm |
| 2019-10-15 | 5401-041-0910 | 0.740 ppm |
| 2019-10-15 | 5401-040-0825 | 0.780 ppm |
| 2019-10-15 | 5401-038-0925 | 0.750 ppm |