Fluoride
Dierks Water Works
Fluoride occurs naturally in surface and groundwater and is also added to drinking water by many water systems to prevent cavities and support oral health in people.
In 2015, the Department of Health and Human Services updated its recommendation of an optimal level of 0.7 parts per million, or ppm, added to drinking water based on the health benefits of tooth decay prevention. Studies have shown that fluoride added to community water systems at this level reduces dental cavities, especially in children.
And studies have conclusively shown that fluoride in toothpaste and mouthwash can also provide these benefits.
Read More.
Health Concerns
Although the HHS-recommended level of 0.7 ppm can help promote oral health in children and adults, this level is likely too high for bottle-fed babies. EWG recommends that caregivers mix baby formula with fluoride-free water.
And fluoride in water at higher levels can be detrimental for everyone, especially children.
Long-term ingestion of higher levels of fluoride in water increases dental fluorosis, which includes mottling, pitting and weakening of the teeth in children.
A 2024 authoritative assessment by the National Toxicology Program found that higher levels of fluoride exposure, such as drinking water containing more than 1.5 ppm of fluoride, are associated with lower IQ in children. The conclusion was based on studies in human populations outside of the U.S.
Affecting systems with naturally occurring fluoride, 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 fracture. But these effects may occur at lower levels of exposure, raising concerns that the current limit may not adequately protect public health.
Samples
Samples exceeding legal limit (MCL)
Samples exceeding
health guidelines
Testing results - average by year
| Year | Average result | Samples taken | Detections | Range of results |
|---|---|---|---|---|
| 2018 | 0.784 ppm | 13 | 13 | 0.460 ppm - 0.920 ppm |
| 2019 | 0.743 ppm | 13 | 13 | 0.580 ppm - 0.890 ppm |
| 2020 | 0.909 ppm | 12 | 12 | 0.630 ppm - 1.26 ppm |
| 2021 | 0.635 ppm | 13 | 13 | 0.410 ppm - 0.890 ppm |
| 2022 | 0.636 ppm | 13 | 13 | 0.580 ppm - 0.710 ppm |
| 2023 | 0.698 ppm | 13 | 13 | 0.560 ppm - 0.780 ppm |
ppm = parts per million
State, National, and Health Guidelines for Drinking Water
EPA Maximum Contaminant
Level (MCL): 4 ppm
ppm = parts per million
All test results
| Date | Lab ID | Result |
|---|---|---|
| 2018-01-03 | Y180180025 | 0.720 ppm |
| 2018-02-06 | Y180520017 | 0.460 ppm |
| 2018-02-13 | Y180460002 | 0.860 ppm |
| 2018-03-06 | Y180720004 | 0.700 ppm |
| 2018-04-03 | Y180990036 | 0.780 ppm |
| 2018-05-02 | Y181300037 | 0.870 ppm |
| 2018-06-05 | Y181620051 | 0.860 ppm |
| 2018-07-05 | Y181970004 | 0.860 ppm |
| 2018-08-01 | Y182190029 | 0.830 ppm |
| 2018-09-05 | Y182530029 | 0.920 ppm |
| 2018-10-02 | Y182810032 | 0.700 ppm |
| 2018-11-01 | Y183170007 | 0.830 ppm |
| 2018-12-04 | Y183440059 | 0.800 ppm |
| 2019-01-02 | Y190070010 | 0.700 ppm |
| 2019-01-15 | Y190170016 | 0.730 ppm |
| 2019-02-07 | Y190500027 | 0.670 ppm |
| 2019-03-04 | Y190700047 | 0.670 ppm |
| 2019-04-04 | Y191050006 | 0.660 ppm |
| 2019-05-01 | Y191260025 | 0.580 ppm |
| 2019-06-04 | Y191610057 | 0.740 ppm |
| 2019-07-02 | Y191890015 | 0.860 ppm |
| 2019-08-01 | Y192250059 | 0.750 ppm |
| 2019-09-03 | Y192540024 | 0.720 ppm |
| 2019-10-03 | Y192880049 | 0.890 ppm |
| 2019-11-04 | Y193180017 | 0.860 ppm |
| 2019-12-02 | Y193470037 | 0.830 ppm |
| 2020-01-07 | Y200120049 | 0.840 ppm |
| 2020-01-29 | Y200300001 | 0.760 ppm |
| 2020-02-03 | Y200410019 | 0.890 ppm |
| 2020-04-06 | Y201060031 | 0.900 ppm |
| 2020-05-07 | Y201410009 | 0.910 ppm |
| 2020-06-05 | Y201670011 | 0.950 ppm |
| 2020-07-06 | Y201950023 | 1.02 ppm |
| 2020-08-03 | Y202310013 | 1.26 ppm |
| 2020-09-09 | Y202610019 | 1.08 ppm |
| 2020-10-06 | Y202880012 | 1.03 ppm |
| 2020-11-10 | Y203220006 | 0.630 ppm |
| 2020-12-01 | Y203400004 | 0.640 ppm |
| 2021-01-04 | Y210080009 | 0.840 ppm |
| 2021-01-26 | Y210280007 | 0.870 ppm |
| 2021-02-03 | Y210400003 | 0.410 ppm |
| 2021-03-01 | Y210640032 | 0.680 ppm |
| 2021-04-05 | Y210990011 | 0.630 ppm |
| 2021-05-03 | Y211270002 | 0.890 ppm |
| 2021-06-02 | Y211590001 | 0.570 ppm |
| 2021-07-07 | Y211940003 | 0.510 ppm |
| 2021-08-04 | Y212210002 | 0.590 ppm |
| 2021-09-02 | Y212520027 | 0.540 ppm |
| 2021-10-06 | Y212840007 | 0.600 ppm |
| 2021-11-08 | Y213220035 | 0.590 ppm |
| 2021-12-01 | Y213420031 | 0.540 ppm |
| 2022-01-03 | Y220110020 | 0.660 ppm |
| 2022-01-11 | Y220130003 | 0.620 ppm |
| 2022-02-02 | Y220400011 | 0.580 ppm |
| 2022-03-03 | Y220680002 | 0.640 ppm |
| 2022-04-05 | Y221010014 | 0.640 ppm |
| 2022-05-06 | Y221310019 | 0.590 ppm |
| 2022-06-03 | Y221590001 | 0.600 ppm |
| 2022-07-06 | Y222070008 | 0.580 ppm |
| 2022-08-01 | Y222180005 | 0.630 ppm |
| 2022-09-01 | Y222500024 | 0.700 ppm |
| 2022-10-04 | Y222830011 | 0.640 ppm |
| 2022-11-03 | Y223130023 | 0.680 ppm |
| 2022-12-01 | Y223400005 | 0.710 ppm |
| 2023-01-03 | Y230100018 | 0.750 ppm |
| 2023-01-11 | Y230110009 | 0.700 ppm |
| 2023-02-01 | Y230380006 | 0.770 ppm |
| 2023-03-01 | Y230650004 | 0.730 ppm |
| 2023-04-03 | Y231000020 | 0.750 ppm |
| 2023-05-03 | Y231290005 | 0.760 ppm |
| 2023-06-05 | Y231600009 | 0.780 ppm |
| 2023-07-06 | Y231920056 | 0.690 ppm |
| 2023-08-01 | Y232190026 | 0.600 ppm |
| 2023-09-05 | Y232550025 | 0.690 ppm |
| 2023-10-02 | Y232840027 | 0.680 ppm |
| 2023-11-01 | Y233100023 | 0.620 ppm |
| 2023-12-05 | Y233520003 | 0.560 ppm |