Fluoride
Silver City Water Supply
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 | 0.833 ppm | 12 | 12 | 0.500 ppm - 1.10 ppm |
| 2015 | 0.725 ppm | 12 | 12 | 0.200 ppm - 0.900 ppm |
| 2016 | 0.917 ppm | 12 | 12 | 0.600 ppm - 2.00 ppm |
| 2017 | 0.625 ppm | 12 | 12 | 0.200 ppm - 0.900 ppm |
| 2018 | 0.621 ppm | 12 | 12 | 0.0500 ppm - 1.10 ppm |
| 2019 | 0.825 ppm | 12 | 12 | 0.600 ppm - 1.000 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 |
|---|---|---|
| 2014-01-21 | 2029459 | 0.900 ppm |
| 2014-02-24 | 2036145 | 0.900 ppm |
| 2014-03-11 | 2040037 | 0.900 ppm |
| 2014-04-07 | 2044412 | 0.900 ppm |
| 2014-05-13 | 2052494 | 1.10 ppm |
| 2014-06-09 | 2056744 | 1.000 ppm |
| 2014-07-08 | 2062988 | 0.800 ppm |
| 2014-08-12 | 2072027 | 1.10 ppm |
| 2014-09-09 | 2076852 | 0.500 ppm |
| 2014-10-14 | 2086373 | 0.700 ppm |
| 2014-11-18 | 2093075 | 0.600 ppm |
| 2014-12-09 | 2098000 | 0.600 ppm |
| 2015-01-13 | 1A50591-01 | 0.500 ppm |
| 2015-02-10 | 1B50569-01 | 0.500 ppm |
| 2015-03-10 | 1C50525-01 | 0.200 ppm |
| 2015-04-07 | 1D50450-01 | 0.800 ppm |
| 2015-05-12 | 1E50742-01 | 0.900 ppm |
| 2015-06-09 | 1F50647-01 | 0.800 ppm |
| 2015-07-14 | 1G51052-02 | 0.800 ppm |
| 2015-08-18 | 1H51283-02 | 0.900 ppm |
| 2015-09-08 | 1I50480-02 | 0.800 ppm |
| 2015-10-19 | 1J51381-02 | 0.900 ppm |
| 2015-11-16 | 1K51062-02 | 0.800 ppm |
| 2015-12-15 | 1L51143-02 | 0.800 ppm |
| 2016-01-13 | 1A60883-02 | 0.900 ppm |
| 2016-02-09 | 1B60501-02 | 0.900 ppm |
| 2016-03-09 | 1C60676-02 | 0.600 ppm |
| 2016-04-12 | 1D60909-02 | 2.00 ppm |
| 2016-05-16 | 1E61181-02 | 0.700 ppm |
| 2016-06-20 | 1F61517-02 | 0.900 ppm |
| 2016-07-11 | 1G60689-02 | 1.000 ppm |
| 2016-08-10 | 1H60917-02 | 0.800 ppm |
| 2016-09-14 | 1I61029-02 | 0.800 ppm |
| 2016-10-11 | 1J60752-02 | 0.900 ppm |
| 2016-11-08 | 1K60685-02 | 0.700 ppm |
| 2016-12-06 | 1L60396-02 | 0.800 ppm |
| 2017-01-09 | 1A70482-02 | 0.400 ppm |
| 2017-02-23 | 1B71565-02 | 0.700 ppm |
| 2017-03-14 | 1C70948-02 | 0.900 ppm |
| 2017-04-04 | 1D70222-02 | 0.900 ppm |
| 2017-05-15 | 1E71244-02 | 0.700 ppm |
| 2017-06-06 | 1F70424-02 | 0.800 ppm |
| 2017-07-11 | 1G70667-02 | 0.800 ppm |
| 2017-08-22 | 1H71769-02 | 0.700 ppm |
| 2017-09-12 | 1I70764-02 | 0.300 ppm |
| 2017-10-17 | 1J71334-02 | 0.600 ppm |
| 2017-11-08 | 1K70756-02 | 0.500 ppm |
| 2017-12-12 | 1L70868-02 | 0.200 ppm |
| 2018-01-09 | 1A80563-02 | 0.300 ppm |
| 2018-02-13 | 1B80870-02 | 1.000 ppm |
| 2018-03-14 | 1C81122-02 | 0.600 ppm |
| 2018-04-10 | 1D80756-02 | 0.700 ppm |
| 2018-05-21 | 1E81804-02 | 0.500 ppm |
| 2018-06-19 | 1F81618-02 | 0.600 ppm |
| 2018-07-10 | 1G80700-02 | 0.700 ppm |
| 2018-08-20 | 1H81685-02 | 0.0500 ppm |
| 2018-09-11 | 1I80726-02 | 1.10 ppm |
| 2018-10-16 | 1J81438-02 | 0.500 ppm |
| 2018-11-19 | 1K81498-02 | 0.700 ppm |
| 2018-12-11 | 1L80710-02 | 0.700 ppm |
| 2019-01-15 | 1A91136-02 | 0.600 ppm |
| 2019-02-19 | 1B91229-02 | 0.800 ppm |
| 2019-03-05 | 1C90234-02 | 0.900 ppm |
| 2019-04-16 | 1D91414-02 | 1.000 ppm |
| 2019-05-08 | 1E90743-02 | 0.900 ppm |
| 2019-06-11 | 1F90754-02 | 0.900 ppm |
| 2019-07-15 | 1G91304-02 | 0.900 ppm |
| 2019-08-06 | 1H90400-02 | 0.800 ppm |
| 2019-09-10 | 1I90675-02 | 0.700 ppm |
| 2019-10-08 | 1J90724-02 | 0.800 ppm |
| 2019-11-18 | 1K91306-02 | 0.700 ppm |
| 2019-12-17 | 1L91420-02 | 0.900 ppm |