Well Water and Fluoride FAQs - Engineering Fact Sheet- Community Water Fluoridation

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Centers for Disease Control and Prevention

Fact Sheet: Private Well Water and Fluoride FAQs

This fact sheet addresses questions that consumers may have on fluoride levels in groundwater from private wells.

How do I know if my water is from a public water system or a private well?
The U.S. Environmental Protection Agency defines a Public Water System as a system that serves 25 or more people per day. If you have water service from a well that has a limited delivery, such as to your house but not to your neighbor’s house, then you likely have a private well.

What are the governmental regulations for private wells?
Although most U.S. households are connected to a public water system, the U.S. Geological Survey estimates that approximately 15% of U.S. residents rely on private wells that are not regulated by EPA Safe Drinking Water Act. In most states, private wells are not regulated by governmental regulatory entities. Therefore, it is the responsibility of the homeowner to know and understand the quality of the water from their well. The U.S. Environmental Protection Agency suggests that all wells should be tested for quality once every three years since influences to well water quality can change over time. Contact your public health office for their advice on testing of private wells in your state or area. Additional information on testing well water quality in private wells serving homes can be found on the U.S. Environmental Protection Agency Web site.

My home gets its water from a private well. What do I need to know about fluoride and groundwater from a well?
Fluoride is present in virtually all waters at some level, and it is important to know the fluoride content of your water, particularly if you have children. If you have a home well, it is recommended to have a sample of your water analyzed by a laboratory. Check with your dentist, physician, or public health department to learn how to have your home well water tested.

What should I do if the water from my well has less fluoride than what is recommended ( 0.6 mg/L)? Can I add fluoride?
The optimum fluoride level in water for good oral health is between 0.7 to 1.2 mg/L (milligrams per liter). If you have water fluoride levels under 0.6 mg/L, your child's dentist or pediatrician should evaluate whether your child can benefit from daily fluoride supplements. Their recommendation will depend on your child's risk of developing tooth decay and as well as exposure to other sources of fluoride (e.g., drinking water at school or daycare, toothpaste). It is not feasible to add fluoride to an individual residence’s well.

What should I do if the water from my well has fluoride over 1.2 mg/L?
Drinking water with fluoride levels greater than 1.2 mg/L is higher than the optimum recommendation. Fluoride levels greater than 1.2 mg/L continue to provide beneficial protection against tooth decay, but at increased levels children aged 8 years and younger that are still developing teeth will have an increased chance of developing enamel fluorosis. If your water has a fluoride level greater than 2 mg/L but less than 4 mg/L, you should consider an alternate source of drinking water for young children. Adults and children older than age 8 years can safely consume the water at these levels, If the fluoride content in your well water is greater than 4 mg/L, consider an alternate source of water for your family, or install a device to remove the fluoride from the water.

What should I do if my well water was measured as having too much fluoride (level greater than 4 mg/L)?
It is unusual to have the fluoride content of water exceed 4 mg/L. If a laboratory report indicates that you have such excessive fluoride content, it is recommended that the water be retested. At least four samples should be collected, a minimum of one week apart, and the results compared. If one sample is above 4 mg/L and the other samples are less than 4 mg/L, then the high value may have been an erroneous measurement. If all samples register excessive levels greater than 4 mg/L, then you may want to consider investigating alternate sources of water for drinking and cooking, or installing a device to remove the fluoride from your home water source. Physical contact with high fluoride content water, such as bathing or dishwashing, is safe since fluoride does not pass through the skin.

What are the health risks of consuming water with fluoride levels greater than 4 mg/L?
Children aged 8 years and younger have an increased chance of developing severe tooth enamel fluorosis. Consumption over a lifetime may increase the likelihood of bone fractures, and may result in skeletal fluorosis, a painful or even crippling disease. The U.S. Environmental Protection Agency has determined that safe exposure of fluoride is below 4 mg/L in drinking water to avoid those effects. The National Research Council recently completed a report on health effects of excessively high fluoride consumption, and CDC has a Statement on the 2006 National Research Council (NRC) Report on Fluoride in Drinking Water .

Will using a home water filtration system take the fluoride out of my home’s water?
Removal of fluoride from water is difficult. Most home point-of-use treatment systems that are installed at single faucets use activated carbon filtration, which does not remove the fluoride. Reverse osmosis point-of-use devices can effectively remove fluoride although the amount may vary given individual circumstances. For a home point-of-use device to claim a reduction in fluoride, it must meet National Sanitation Foundation (NSF) Standard 58 criteria for fluoride removal. Standard 58 requires that a device must achieve a 1.5 milligrams per liter (mg/L) concentration in the product water if the original concentration was 8.0 mg/L, or approximately 80 percent removal. This percentage removal may not be consistent at lower concentrations of fluoride. Check with the manufacturer of the individual product for specific product information. Fluoride is not released from water when it is boiled or frozen. One exception would be a water distillation system. These systems heat water to the boiling point and then collect water vapor as it evaporates. Water distillation systems are typically used in laboratories. For home use, these systems can be expensive and may present safety and maintenance concerns.

Can I use water with fluoride for preparing infant formula?
Yes. People have used optimally fluoridated tap water to prepare infant formula for many years. However, if your infant is exclusively consuming formula reconstituted with optimally fluoridated water (0.7 to 1.2 ppm or mg/l), there may be an increased potential for them to develop mild dental fluorosis on their developing teeth. Consult with your pediatrician for proper infant formula feeding advice. Additional information can be found in a fact sheet on Infant Formula.