Fluoride
El Monte Water Department
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 | 0.470 ppm | 12 | 12 | 0.275 ppm - 0.714 ppm |
| 2015 | 0.460 ppm | 9 | 9 | 0.303 ppm - 0.680 ppm |
| 2016 | 0.468 ppm | 13 | 13 | 0.273 ppm - 0.684 ppm |
| 2017 | 0.424 ppm | 18 | 18 | 0.227 ppm - 0.631 ppm |
| 2018 | 0.389 ppm | 16 | 16 | 0.269 ppm - 0.528 ppm |
| 2019 | 0.641 ppm | 33 | 33 | 0.284 ppm - 1.000 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 | 4792-006-1125 | 0.275 ppm |
| 2014-03-04 | 4792-009-1200 | 0.652 ppm |
| 2014-04-24 | 9588-006-1005 | 0.320 ppm |
| 2014-06-03 | 4792-002-1230 | 0.478 ppm |
| 2014-06-03 | 4792-006-1120 | 0.330 ppm |
| 2014-06-03 | 4792-009-1335 | 0.714 ppm |
| 2014-07-28 | 9588-002-1050 | 0.450 ppm |
| 2014-09-02 | 4792-002-1320 | 0.428 ppm |
| 2014-09-02 | 4792-006-1355 | 0.322 ppm |
| 2014-09-02 | 4792-009-1205 | 0.660 ppm |
| 2014-12-02 | 4792-006-1400 | 0.315 ppm |
| 2014-12-02 | 4792-009-1425 | 0.690 ppm |
| 2015-03-03 | 4792-002-1125 | 0.368 ppm |
| 2015-03-03 | 4792-006-1020 | 0.303 ppm |
| 2015-03-03 | 4792-009-1145 | 0.591 ppm |
| 2015-06-03 | 4792-002-1300 | 0.440 ppm |
| 2015-06-03 | 4792-006-1155 | 0.303 ppm |
| 2015-06-03 | 4792-009-0825 | 0.680 ppm |
| 2015-09-01 | 4792-002-1410 | 0.484 ppm |
| 2015-09-01 | 4792-006-1310 | 0.316 ppm |
| 2015-09-01 | 4792-009-1115 | 0.653 ppm |
| 2016-06-07 | 4792-002-0945 | 0.388 ppm |
| 2016-06-07 | 4792-006-0925 | 0.287 ppm |
| 2016-06-07 | 4792-008-1045 | 0.465 ppm |
| 2016-06-07 | 4792-009-1100 | 0.607 ppm |
| 2016-07-07 | 9588-008-1015 | 0.390 ppm |
| 2016-07-07 | 9588-009-0950 | 0.650 ppm |
| 2016-09-06 | 4792-002-0900 | 0.459 ppm |
| 2016-09-06 | 4792-006-1000 | 0.273 ppm |
| 2016-09-06 | 4792-008-0830 | 0.447 ppm |
| 2016-09-06 | 4792-009-0800 | 0.684 ppm |
| 2016-12-06 | 4792-006-1010 | 0.358 ppm |
| 2016-12-06 | 4792-008-1130 | 0.489 ppm |
| 2016-12-06 | 4792-009-1140 | 0.582 ppm |
| 2017-03-07 | 4792-002-0850 | 0.451 ppm |
| 2017-03-07 | 4792-006-0755 | 0.291 ppm |
| 2017-03-07 | 4792-008-1005 | 0.498 ppm |
| 2017-03-07 | 4792-009-1035 | 0.631 ppm |
| 2017-04-27 | 9588-006-1435 | 0.290 ppm |
| 2017-06-06 | 4792-002-0900 | 0.410 ppm |
| 2017-06-06 | 4792-006-0930 | 0.255 ppm |
| 2017-06-06 | 4792-009-0715 | 0.528 ppm |
| 2017-08-03 | 9588-002-1010 | 0.430 ppm |
| 2017-09-05 | 4792-002-1040 | 0.358 ppm |
| 2017-09-05 | 4792-006-0940 | 0.227 ppm |
| 2017-09-05 | 4792-008-1145 | 0.320 ppm |
| 2017-09-05 | 4792-009-1050 | 0.520 ppm |
| 2017-09-27 | 4792-002-1010 | 0.533 ppm |
| 2017-12-06 | 4792-002-0755 | 0.489 ppm |
| 2017-12-06 | 4792-006-1130 | 0.327 ppm |
| 2017-12-06 | 4792-008-1130 | 0.474 ppm |
| 2017-12-06 | 4792-009-0855 | 0.598 ppm |
| 2018-03-06 | 4792-002-0935 | 0.437 ppm |
| 2018-03-06 | 4792-006-1000 | 0.269 ppm |
| 2018-03-06 | 4792-008-0820 | 0.418 ppm |
| 2018-03-06 | 4792-009-0705 | 0.528 ppm |
| 2018-06-05 | 4792-002-0920 | 0.344 ppm |
| 2018-06-05 | 4792-006-0940 | 0.306 ppm |
| 2018-06-05 | 4792-008-0815 | 0.419 ppm |
| 2018-06-05 | 4792-009-0700 | 0.507 ppm |
| 2018-09-05 | 4792-002-1050 | 0.337 ppm |
| 2018-09-05 | 4792-006-1125 | 0.306 ppm |
| 2018-09-05 | 4792-008-0850 | 0.430 ppm |
| 2018-09-05 | 4792-009-0725 | 0.305 ppm |
| 2018-12-04 | 4792-002-1025 | 0.346 ppm |
| 2018-12-04 | 4792-006-1055 | 0.318 ppm |
| 2018-12-04 | 4792-008-0925 | 0.447 ppm |
| 2018-12-04 | 4792-009-0810 | 0.502 ppm |
| 2019-03-05 | 4792-002-1235 | 0.708 ppm |
| 2019-03-05 | 4792-006-1025 | 0.655 ppm |
| 2019-03-05 | 4792-008-1410 | 0.749 ppm |
| 2019-03-05 | 4792-009-0955 | 0.789 ppm |
| 2019-03-08 | 4792-043-1210 | 0.792 ppm |
| 2019-03-08 | 4792-044-1045 | 0.722 ppm |
| 2019-03-08 | 4792-045-1135 | 0.777 ppm |
| 2019-05-28 | 9588-043-1310 | 1.000 ppm |
| 2019-05-28 | 9588-044-1240 | 0.790 ppm |
| 2019-05-28 | 9588-045-1255 | 0.790 ppm |
| 2019-06-05 | 4792-002-1220 | 0.380 ppm |
| 2019-06-05 | 4792-006-1055 | 0.306 ppm |
| 2019-06-05 | 4792-008-0910 | 0.434 ppm |
| 2019-06-05 | 4792-009-0750 | 0.585 ppm |
| 2019-06-05 | 4792-043-1440 | 0.845 ppm |
| 2019-06-05 | 4792-044-1355 | 0.655 ppm |
| 2019-06-05 | 4792-045-1420 | 0.665 ppm |
| 2019-07-25 | 9588-008-1445 | 0.410 ppm |
| 2019-07-25 | 9588-009-1430 | 0.640 ppm |
| 2019-09-03 | 4792-002-1015 | 0.448 ppm |
| 2019-09-03 | 4792-006-0935 | 0.284 ppm |
| 2019-09-03 | 4792-008-0905 | 0.496 ppm |
| 2019-09-03 | 4792-009-0750 | 0.681 ppm |
| 2019-09-03 | 4792-043-1320 | 0.904 ppm |
| 2019-09-03 | 4792-044-1230 | 0.691 ppm |
| 2019-09-03 | 4792-045-1255 | 0.719 ppm |
| 2019-12-03 | 4792-002-1005 | 0.727 ppm |
| 2019-12-03 | 4792-006-0745 | 0.318 ppm |
| 2019-12-03 | 4792-008-0950 | 0.453 ppm |
| 2019-12-03 | 4792-009-0820 | 0.640 ppm |
| 2019-12-05 | 4792-043-0830 | 0.814 ppm |
| 2019-12-05 | 4792-044-0730 | 0.666 ppm |
| 2019-12-05 | 4792-045-0800 | 0.634 ppm |