Fluoride
Danbury Water Department
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 | 0.358 ppm | 4 | 4 | 0.0300 ppm - 0.650 ppm |
| 2019 | 0.302 ppm | 5 | 5 | 0.0400 ppm - 0.730 ppm |
| 2020 | 0.318 ppm | 4 | 2 | ND - 0.680 ppm |
| 2021 | 0.348 ppm | 4 | 2 | ND - 0.710 ppm |
| 2022 | 0.275 ppm | 4 | 2 | ND - 0.600 ppm |
| 2023 | 0.385 ppm | 4 | 2 | ND - 0.810 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 |
|---|---|---|
| 2018-04-12 | 212690GE | 0.110 ppm |
| 2018-04-12 | 212687GE | 0.0300 ppm |
| 2018-10-12 | IOC1 200508940 | 0.640 ppm |
| 2018-10-12 | IOC1 200508939 | 0.650 ppm |
| 2019-04-11 | IOC1 200528182 | 0.730 ppm |
| 2019-04-11 | IOC1 200528181 | 0.620 ppm |
| 2019-04-11 | IOCR 200528185 | 0.0500 ppm |
| 2019-04-11 | IOCR 200528187 | 0.0400 ppm |
| 2019-05-16 | IOCR 200532591A | 0.0700 ppm |
| 2020-08-20 | IOCR 200587329 | ND |
| 2020-08-20 | IOCR 200587327 | ND |
| 2020-08-20 | IOC1 200587328 | 0.680 ppm |
| 2020-08-20 | IOC1 200587330 | 0.590 ppm |
| 2021-04-15 | IOC1 200613297 | 0.710 ppm |
| 2021-04-15 | IOC1 200613295 | 0.680 ppm |
| 2021-04-15 | IOCR 200613294 | ND |
| 2021-04-15 | IOCR 200613296 | ND |
| 2022-06-07 | 287329 | 0.600 ppm |
| 2022-06-07 | 287325 | 0.500 ppm |
| 2022-06-07 | 287323 | ND |
| 2022-06-07 | 287327 | ND |
| 2023-01-12 | 304532 | ND |
| 2023-01-12 | 304533 | ND |
| 2023-05-15 | N3E0590-02PPS | 0.810 ppm |
| 2023-05-15 | N3E0590-01PPS | 0.728 ppm |