Fluoride
Metropolitan Utilities 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.
Testing results - average by year
Year | Average result | Samples taken | Detections | Range of results |
---|---|---|---|---|
2013 | N/A | 0 | 0 | N/A |
2014 | 0.594 ppm | 21 | 20 | ND - 0.915 ppm |
2015 | 0.856 ppm | 12 | 12 | 0.747 ppm - 0.917 ppm |
2016 | 0.712 ppm | 15 | 15 | 0.242 ppm - 0.969 ppm |
2017 | 0.782 ppm | 12 | 12 | 0.610 ppm - 0.901 ppm |
2018 | 0.691 ppm | 12 | 12 | 0.352 ppm - 0.868 ppm |
2019 | 0.658 ppm | 15 | 14 | ND - 0.924 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 |
---|---|---|
2014-01-06 | 280511 | 0.769 ppm |
2014-02-24 | 285594 | 0.798 ppm |
2014-03-10 | 289482 | 0.843 ppm |
2014-04-02 | 292900 | 0.750 ppm |
2014-05-05 | 294065 | 0.263 ppm |
2014-05-05 | 294066 | 0.243 ppm |
2014-05-05 | 294068 | 0.284 ppm |
2014-05-05 | 294069 | 0.299 ppm |
2014-05-05 | 294071 | 0.239 ppm |
2014-05-06 | 294064 | 0.773 ppm |
2014-05-06 | 294067 | 0.251 ppm |
2014-05-06 | 294070 | 0.331 ppm |
2014-05-06 | 298720 | 0.762 ppm |
2014-06-02 | 303187 | ND |
2014-06-02 | 304840 | 0.818 ppm |
2014-07-14 | 311209 | 0.831 ppm |
2014-08-04 | 316518 | 0.873 ppm |
2014-09-03 | 322203 | 0.805 ppm |
2014-10-06 | 327106 | 0.768 ppm |
2014-11-12 | 334522 | 0.915 ppm |
2014-12-02 | 338032 | 0.857 ppm |
2015-01-12 | 342041 | 0.832 ppm |
2015-02-09 | 347665 | 0.917 ppm |
2015-03-02 | 350539 | 0.873 ppm |
2015-04-14 | 355429 | 0.879 ppm |
2015-05-11 | 363189 | 0.853 ppm |
2015-06-02 | 367499 | 0.747 ppm |
2015-07-06 | 371751 | 0.891 ppm |
2015-08-05 | 379981 | 0.897 ppm |
2015-09-08 | 385261 | 0.867 ppm |
2015-10-05 | 390261 | 0.829 ppm |
2015-11-09 | 397216 | 0.849 ppm |
2015-12-07 | 401151 | 0.837 ppm |
2016-01-05 | 0.835 ppm | |
2016-02-08 | 0.729 ppm | |
2016-03-07 | 0.720 ppm | |
2016-04-06 | 0.414 ppm | |
2016-04-12 | 0.711 ppm | |
2016-04-12 | 0.242 ppm | |
2016-05-03 | 0.794 ppm | |
2016-06-06 | 0.765 ppm | |
2016-07-12 | 0.830 ppm | |
2016-07-13 | 0.781 ppm | |
2016-08-10 | 0.829 ppm | |
2016-09-07 | 0.969 ppm | |
2016-10-12 | 0.863 ppm | |
2016-11-10 | 0.895 ppm | |
2016-12-07 | 0.307 ppm | |
2017-01-04 | 0.698 ppm | |
2017-02-06 | 0.857 ppm | |
2017-03-07 | 0.825 ppm | |
2017-04-03 | 0.814 ppm | |
2017-05-02 | 0.610 ppm | |
2017-06-05 | 0.901 ppm | |
2017-07-05 | 0.789 ppm | |
2017-08-14 | 0.818 ppm | |
2017-09-11 | 0.787 ppm | |
2017-10-11 | 0.767 ppm | |
2017-11-08 | 0.777 ppm | |
2017-12-06 | 0.736 ppm | |
2018-01-02 | 530190 | 0.776 ppm |
2018-02-13 | 535765 | 0.762 ppm |
2018-03-12 | 539246 | 0.781 ppm |
2018-04-04 | 542538 | 0.744 ppm |
2018-05-08 | 548761 | 0.352 ppm |
2018-06-11 | 553983 | 0.649 ppm |
2018-07-10 | 558642 | 0.356 ppm |
2018-08-13 | 566392 | 0.868 ppm |
2018-09-11 | 570594 | 0.843 ppm |
2018-10-01 | 576532 | 0.677 ppm |
2018-11-19 | 582028 | 0.718 ppm |
2018-12-04 | 585855 | 0.762 ppm |
2019-01-07 | 589275 | 0.755 ppm |
2019-02-04 | 594704 | 0.761 ppm |
2019-03-04 | 598105 | 0.726 ppm |
2019-04-08 | 601972 | 0.526 ppm |
2019-05-14 | 609592 | 0.683 ppm |
2019-06-10 | 603527 | 0.683 ppm |
2019-06-10 | 603528 | ND |
2019-06-10 | 613506 | 0.712 ppm |
2019-07-08 | 619493 | 0.682 ppm |
2019-07-15 | 622141 | 0.684 ppm |
2019-08-13 | 627284 | 0.924 ppm |
2019-09-09 | 631495 | 0.699 ppm |
2019-10-15 | 636769 | 0.737 ppm |
2019-11-05 | 643513 | 0.672 ppm |
2019-12-10 | 648255 | 0.632 ppm |