Drinking Water: Fluoride
What is fluoride?
Fluoride is a naturally occurring mineral that is found in rocks, soil, and water. Fluoride is added to some dental products (toothpastes, mouth rinses, and varnishes) to prevent tooth decay. Dentists or doctors may prescribe fluoride supplements to children at high risk for tooth decay.
How can fluoride affect my health?
Fluoride is used to help prevent cavities and support the development of strong teeth. However, moderate levels of fluoride can change teeth’s appearance in young children and high levels can cause bones to became brittle and fragile.
How do I consume fluoride?
The most common ways that people can consume fluoride is through dental products, supplements, and drinking water.
People can consume fluoride from drinking water as it is naturally present in groundwater. Most groundwater has very low fluoride levels. Because of this, some public water systems add fluoride to the water to help prevent tooth decay in their community - this process is known as community water fluoridation. However, some groundwater can have high levels of fluoride and people may need to reduce their consumption of this water.
When should I take action about fluoride in my drinking water?
Public water systems are required to test for fluoride on a regular basis.
If the fluoride level is less than 0.7 milligrams per liter (mg/L), check with your dental or health care provider to see if you or your family members should take additional steps to prevent cavities and tooth decay. You can find your community's fluoride level online.
If the fluoride level in your water is high (more than 2 mg/L), the system will issue a public notice. The public notice will include information on the levels detected, the actions that the system is taking to address the problem, and any steps that you should take to reduce you and your family's fluoride exposure.
Private well users should test for fluoride at least once using a Wisconsin certified lab.
- Households with pregnant people and young children may be eligible for free testing through their local health department.
If the fluoride level is below 0.7 milligrams per liter (mg/L):
- Check with your child’s dental or health care provider to see if they would benefit from fluoride supplementation.
If the fluoride level is between 0.7 and 2 mg/L:
- No additional action is needed.
If the fluoride level is between 2 and 4 mg/L:
- Children 8 and younger should use a different source of water for drinking. Also use a different source of water to prepare foods that take up lot of water (like rice, oatmeal, and gelatin) and to make baby formula.
- Options include bottled water, water from a well that is not affected, and water from a public water system.
- The water can still be used for bathing, brushing teeth, and washing dishes.
If the fluoride level is above 4 mg/L:
- Everyone should use a different source of water for drinking and making foods that take up a lot of water.
- The water can still be used for bathing, brushing teeth, and washing dishes.
- Find a long-term solution. Options include installing a certified treatment device and drilling a new well.
- Our Water Treatment Devices for Private Well Contaminants fact sheet, P-45012 (PDF) has information on certified treatment devices for fluoride.
- The Wisconsin Department of Natural Resource's well compensation grants provide funds to address public health hazards in private wells.
Our Fluoride in Private Well Water fact sheet, P-03521 (PDF) has these steps in printable format.
Who regulates fluoride in Wisconsin?
The Wisconsin Department of Natural Resources (DNR) regulates how much fluoride can be released into groundwater in Wisconsin and how much can be in water served by public water systems.
Related topics
Our groundwater standards page has information on how Wisconsin's groundwater standards are set, DHS' role in the process, and a summary of the current and recommended standards including fluoride.
Our fluoride and community water fluoridation page has more information on how fluoride prevents tooth decay.
The CDC (Center for Disease Control and Prevention) community water fluoridation page also has information on community water fluoridation and its benefits for oral health.
The Agency for Toxic Substances and Disease Registry ToxFAQs page has more information on fluoride exposure routes and health effects.