Fluoride
Helena Water Sewer
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 | 0.658 ppm | 13 | 13 | 0.530 ppm - 0.780 ppm |
| 2015 | 0.727 ppm | 12 | 12 | 0.460 ppm - 0.890 ppm |
| 2016 | 0.844 ppm | 12 | 12 | 0.800 ppm - 0.900 ppm |
| 2017 | 0.817 ppm | 13 | 13 | 0.570 ppm - 0.950 ppm |
| 2018 | 0.778 ppm | 12 | 12 | 0.720 ppm - 0.840 ppm |
| 2019 | 0.799 ppm | 12 | 12 | 0.760 ppm - 0.860 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 |
|---|---|---|
| 2014-01-02 | 140080013 | 0.650 ppm |
| 2014-02-09 | 140490028 | 0.530 ppm |
| 2014-03-13 | 140900004 | 0.560 ppm |
| 2014-04-01 | 141040004 | 0.580 ppm |
| 2014-04-22 | 141140008 | 0.640 ppm |
| 2014-05-13 | 141470007 | 0.640 ppm |
| 2014-06-03 | 141670007 | 0.780 ppm |
| 2014-07-02 | 141950036 | 0.730 ppm |
| 2014-08-07 | 142300007 | 0.660 ppm |
| 2014-09-17 | 142720004 | 0.680 ppm |
| 2014-10-20 | Y143000033 | 0.670 ppm |
| 2014-11-04 | Y143210012 | 0.700 ppm |
| 2014-12-10 | Y143520015 | 0.730 ppm |
| 2015-01-02 | Y150130018 | 0.660 ppm |
| 2015-02-11 | Y150510007 | 0.640 ppm |
| 2015-03-18 | Y150890004 | 0.460 ppm |
| 2015-04-14 | Y151140007 | 0.590 ppm |
| 2015-05-15 | Y151420018 | 0.590 ppm |
| 2015-06-10 | Y151740004 | 0.790 ppm |
| 2015-07-09 | Y152020007 | 0.770 ppm |
| 2015-08-13 | Y152360012 | 0.850 ppm |
| 2015-09-17 | Y152710006 | 0.780 ppm |
| 2015-10-09 | Y152890060 | 0.890 ppm |
| 2015-11-04 | Y153200015 | 0.870 ppm |
| 2015-12-08 | Y153520031 | 0.830 ppm |
| 2016-01-20 | Y160270034 | 0.860 ppm |
| 2016-02-18 | Y160610011 | 0.820 ppm |
| 2016-03-08 | Y160810009 | 0.800 ppm |
| 2016-04-21 | Y161240006 | 0.840 ppm |
| 2016-05-10 | Y161440005 | 0.850 ppm |
| 2016-06-26 | Y161870042 | 0.820 ppm |
| 2016-07-06 | Y162000047 | 0.900 ppm |
| 2016-08-04 | Y162280008 | 0.860 ppm |
| 2016-09-12 | Y162640039 | 0.860 ppm |
| 2016-10-06 | Y162880068 | 0.840 ppm |
| 2016-11-21 | Y163340004 | 0.820 ppm |
| 2016-12-14 | Y163560014 | 0.860 ppm |
| 2017-01-04 | Y170120065 | 0.920 ppm |
| 2017-02-08 | Y170460023 | 0.830 ppm |
| 2017-03-03 | Y170720035 | 0.910 ppm |
| 2017-04-12 | Y171140001 | 0.950 ppm |
| 2017-05-04 | Y171350048 | 0.870 ppm |
| 2017-05-31 | Y171520003 | 0.570 ppm |
| 2017-06-12 | Y171770009 | 0.860 ppm |
| 2017-07-12 | Y172050055 | 0.830 ppm |
| 2017-08-02 | Y172260011 | 0.800 ppm |
| 2017-09-05 | Y172540048 | 0.770 ppm |
| 2017-10-02 | Y172820034 | 0.770 ppm |
| 2017-11-13 | Y173380010 | 0.770 ppm |
| 2017-12-05 | Y173450078 | 0.770 ppm |
| 2018-01-19 | Y180240023 | 0.740 ppm |
| 2018-02-08 | Y180520011 | 0.720 ppm |
| 2018-03-09 | Y180780016 | 0.800 ppm |
| 2018-04-04 | Y180990047 | 0.790 ppm |
| 2018-05-17 | Y181410040 | 0.740 ppm |
| 2018-06-19 | Y181760062 | 0.800 ppm |
| 2018-07-03 | Y181900022 | 0.800 ppm |
| 2018-08-14 | Y182320037 | 0.740 ppm |
| 2018-09-13 | Y182610043 | 0.770 ppm |
| 2018-10-18 | Y183020002 | 0.840 ppm |
| 2018-11-05 | Y183170045 | 0.820 ppm |
| 2018-12-05 | Y183440036 | 0.770 ppm |
| 2019-01-08 | Y190140054 | 0.780 ppm |
| 2019-02-20 | Y190560040 | 0.840 ppm |
| 2019-03-12 | Y190770035 | 0.840 ppm |
| 2019-04-03 | Y191050008 | 0.790 ppm |
| 2019-05-06 | Y191330036 | 0.790 ppm |
| 2019-06-04 | Y191610058 | 0.770 ppm |
| 2019-07-02 | Y191890014 | 0.790 ppm |
| 2019-08-05 | Y192250007 | 0.770 ppm |
| 2019-09-09 | Y192590003 | 0.860 ppm |
| 2019-10-02 | Y192880037 | 0.800 ppm |
| 2019-11-06 | Y193180034 | 0.800 ppm |
| 2019-12-10 | Y193540009 | 0.760 ppm |