Fluoride
City of Granbury
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 | 0.238 ppm | 7 | 7 | 0.152 ppm - 0.328 ppm |
2015 | 0.420 ppm | 3 | 3 | 0.305 ppm - 0.514 ppm |
2016 | 0.504 ppm | 4 | 4 | 0.358 ppm - 0.831 ppm |
2017 | 0.291 ppm | 12 | 12 | 0.168 ppm - 0.552 ppm |
2018 | 0.413 ppm | 3 | 3 | 0.0698 ppm - 0.647 ppm |
2019 | 0.247 ppm | 3 | 3 | 0.153 ppm - 0.417 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 |
---|---|---|
2014-02-26 | Q1406448008 | 0.300 ppm |
2014-07-09 | Q1426808020 | 0.224 ppm |
2014-07-09 | Q1426808019 | 0.287 ppm |
2014-07-09 | Q1426808018 | 0.192 ppm |
2014-07-09 | Q1426808017 | 0.185 ppm |
2014-07-09 | Q1426808016 | 0.328 ppm |
2014-10-22 | Q1453503011 | 0.152 ppm |
2015-06-18 | Q1522966023 | 0.305 ppm |
2015-06-18 | Q1522966022 | 0.442 ppm |
2015-06-18 | Q1522966021 | 0.514 ppm |
2016-01-14 | Q1601671015 | 0.360 ppm |
2016-01-14 | Q1601671014 | 0.468 ppm |
2016-01-14 | Q1601671013 | 0.831 ppm |
2016-01-14 | Q1601671012 | 0.358 ppm |
2017-07-06 | Q1727515036 | 0.245 ppm |
2017-09-19 | Q1744801019 | 0.233 ppm |
2017-09-19 | Q1744801018 | 0.188 ppm |
2017-09-19 | Q1744801017 | 0.234 ppm |
2017-09-19 | Q1744801003 | 0.231 ppm |
2017-09-19 | Q1744801002 | 0.168 ppm |
2017-10-04 | Q1748839016 | 0.290 ppm |
2017-10-04 | Q1748839033 | 0.552 ppm |
2017-10-04 | Q1748839012 | 0.237 ppm |
2017-10-04 | Q1748839032 | 0.437 ppm |
2017-10-04 | Q1748839031 | 0.424 ppm |
2017-10-04 | Q1748839003 | 0.250 ppm |
2018-05-02 | Q1817630006 | 0.0698 ppm |
2018-05-02 | Q1817630020 | 0.521 ppm |
2018-05-02 | Q1817630005 | 0.647 ppm |
2019-03-18 | Q1911097027 | 0.417 ppm |
2019-03-18 | Q1911097026 | 0.153 ppm |
2019-05-09 | Q1923093021 | 0.172 ppm |