Fluoride
California Domestic Water Company
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 | 0.300 ppm | 21 | 21 | 0.230 ppm - 0.370 ppm |
| 2015 | 0.296 ppm | 15 | 15 | 0.260 ppm - 0.320 ppm |
| 2016 | 0.273 ppm | 15 | 15 | 0.220 ppm - 0.300 ppm |
| 2017 | 0.318 ppm | 23 | 23 | 0.260 ppm - 0.380 ppm |
| 2018 | 0.301 ppm | 17 | 17 | 0.250 ppm - 0.330 ppm |
| 2019 | 0.262 ppm | 16 | 16 | 0.220 ppm - 0.300 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 |
|---|---|---|
| 2014-03-21 | 9588-014-0910 | 0.230 ppm |
| 2014-04-07 | 3761-004-0854 | 0.310 ppm |
| 2014-04-07 | 3761-005-0939 | 0.310 ppm |
| 2014-04-07 | 3761-006-0903 | 0.300 ppm |
| 2014-04-07 | 3761-007-0921 | 0.300 ppm |
| 2014-04-07 | 3761-008-0815 | 0.310 ppm |
| 2014-04-07 | 3761-009-0735 | 0.290 ppm |
| 2014-04-07 | 3761-014-1025 | 0.250 ppm |
| 2014-04-09 | 9588-004-1120 | 0.260 ppm |
| 2014-04-09 | 9588-005-1115 | 0.260 ppm |
| 2014-04-09 | 9588-006-1140 | 0.260 ppm |
| 2014-04-09 | 9588-007-1130 | 0.250 ppm |
| 2014-04-09 | 9588-008-1150 | 0.270 ppm |
| 2014-04-09 | 3761-020-0721 | 0.320 ppm |
| 2014-10-06 | 3761-004-0855 | 0.330 ppm |
| 2014-10-06 | 3761-005-1024 | 0.360 ppm |
| 2014-10-06 | 3761-006-0943 | 0.350 ppm |
| 2014-10-06 | 3761-007-1000 | 0.350 ppm |
| 2014-10-06 | 3761-008-0837 | 0.370 ppm |
| 2014-10-06 | 3761-009-0750 | 0.350 ppm |
| 2014-12-16 | 3761-014-0905 | 0.260 ppm |
| 2015-04-06 | 3761-004-0850 | 0.310 ppm |
| 2015-04-06 | 3761-005-0555 | 0.300 ppm |
| 2015-04-06 | 3761-006-0743 | 0.300 ppm |
| 2015-04-06 | 3761-007-0757 | 0.290 ppm |
| 2015-04-06 | 3761-008-0730 | 0.300 ppm |
| 2015-04-06 | 3761-009-0525 | 0.300 ppm |
| 2015-04-06 | 3761-014-0700 | 0.260 ppm |
| 2015-10-05 | 3761-004-0809 | 0.310 ppm |
| 2015-10-05 | 3761-005-0943 | 0.310 ppm |
| 2015-10-05 | 3761-006-0840 | 0.310 ppm |
| 2015-10-05 | 3761-007-0921 | 0.300 ppm |
| 2015-10-05 | 3761-008-0902 | 0.310 ppm |
| 2015-10-05 | 3761-009-0725 | 0.320 ppm |
| 2015-10-05 | 3761-014-1029 | 0.260 ppm |
| 2015-11-19 | 9588-020-1055 | 0.260 ppm |
| 2016-04-04 | 3761-004-0915 | 0.290 ppm |
| 2016-04-04 | 3761-005-1030 | 0.280 ppm |
| 2016-04-04 | 3761-006-1015 | 0.280 ppm |
| 2016-04-04 | 3761-007-0958 | 0.290 ppm |
| 2016-04-04 | 3761-008-0852 | 0.290 ppm |
| 2016-04-04 | 3761-009-0745 | 0.290 ppm |
| 2016-04-04 | 3761-014-1140 | 0.250 ppm |
| 2016-10-03 | 3761-004-0829 | 0.270 ppm |
| 2016-10-03 | 3761-005-0948 | 0.270 ppm |
| 2016-10-03 | 3761-006-0903 | 0.300 ppm |
| 2016-10-03 | 3761-007-0924 | 0.260 ppm |
| 2016-10-03 | 3761-008-0813 | 0.280 ppm |
| 2016-10-03 | 3761-009-0729 | 0.270 ppm |
| 2016-10-03 | 3761-014-1107 | 0.220 ppm |
| 2016-10-03 | 3761-020-1004 | 0.250 ppm |
| 2017-01-10 | 9588-014-0900 | 0.260 ppm |
| 2017-04-03 | 3761-004-0915 | 0.370 ppm |
| 2017-04-03 | 3761-005-1015 | 0.370 ppm |
| 2017-04-03 | 3761-006-0937 | 0.380 ppm |
| 2017-04-03 | 3761-007-0954 | 0.370 ppm |
| 2017-04-03 | 3761-008-0834 | 0.360 ppm |
| 2017-04-03 | 3761-009-0748 | 0.360 ppm |
| 2017-04-03 | 3761-014-1135 | 0.360 ppm |
| 2017-04-03 | 3761-020-1031 | 0.360 ppm |
| 2017-04-05 | 9588-004-0920 | 0.280 ppm |
| 2017-04-05 | 9588-005-0905 | 0.270 ppm |
| 2017-04-05 | 9588-006-0930 | 0.280 ppm |
| 2017-04-05 | 9588-007-0940 | 0.270 ppm |
| 2017-04-05 | 9588-008-0955 | 0.260 ppm |
| 2017-09-26 | 3761-009-0930 | 0.350 ppm |
| 2017-10-02 | 3761-004-0837 | 0.300 ppm |
| 2017-10-02 | 3761-005-0919 | 0.300 ppm |
| 2017-10-02 | 3761-006-1003 | 0.310 ppm |
| 2017-10-02 | 3761-007-0940 | 0.300 ppm |
| 2017-10-02 | 3761-008-0815 | 0.310 ppm |
| 2017-10-02 | 3761-009-0729 | 0.300 ppm |
| 2017-10-02 | 3761-014-1115 | 0.310 ppm |
| 2017-10-02 | 3761-020-1020 | 0.280 ppm |
| 2018-04-02 | 3761-004-0900 | 0.300 ppm |
| 2018-04-02 | 3761-005-1038 | 0.300 ppm |
| 2018-04-02 | 3761-006-0950 | 0.300 ppm |
| 2018-04-02 | 3761-007-1018 | 0.290 ppm |
| 2018-04-02 | 3761-008-0931 | 0.290 ppm |
| 2018-04-02 | 3761-009-0757 | 0.300 ppm |
| 2018-04-02 | 3761-014-1150 | 0.270 ppm |
| 2018-04-02 | 3761-020-1054 | 0.310 ppm |
| 2018-10-01 | 3761-005-1029 | 0.310 ppm |
| 2018-10-01 | 3761-006-0958 | 0.320 ppm |
| 2018-10-01 | 3761-007-0940 | 0.300 ppm |
| 2018-10-01 | 3761-008-0822 | 0.320 ppm |
| 2018-10-01 | 3761-009-0740 | 0.310 ppm |
| 2018-10-01 | 3761-014-1127 | 0.300 ppm |
| 2018-10-01 | 3761-020-1015 | 0.320 ppm |
| 2018-10-04 | 3761-004-0815 | 0.330 ppm |
| 2018-10-09 | 9588-020-0910 | 0.250 ppm |
| 2019-04-01 | 3761-005-1131 | 0.260 ppm |
| 2019-04-01 | 3761-006-0956 | 0.280 ppm |
| 2019-04-01 | 3761-007-0941 | 0.240 ppm |
| 2019-04-01 | 3761-008-0840 | 0.280 ppm |
| 2019-04-01 | 3761-009-0814 | 0.260 ppm |
| 2019-04-01 | 3761-014-1125 | 0.220 ppm |
| 2019-04-01 | 3761-020-1115 | 0.270 ppm |
| 2019-04-08 | 3761-004-0920 | 0.300 ppm |
| 2019-10-07 | 3761-004-0919 | 0.270 ppm |
| 2019-10-07 | 3761-005-1055 | 0.260 ppm |
| 2019-10-07 | 3761-006-1118 | 0.270 ppm |
| 2019-10-07 | 3761-007-1130 | 0.260 ppm |
| 2019-10-07 | 3761-008-0843 | 0.260 ppm |
| 2019-10-07 | 3761-009-0800 | 0.270 ppm |
| 2019-10-07 | 3761-014-0958 | 0.230 ppm |
| 2019-10-07 | 3761-020-1002 | 0.260 ppm |