Protecting Public Health and the Environment.

Fluoride in Drinking Water

Fluoride is a naturally occurring compound derived from fluorine, the earth's 13th most abundant element. It is found in many rocks and minerals in the soil and enters drinking water as water passes through these soils. Fluoride is present naturally in almost all foods and beverages including water, but levels can vary widely. Very few public water systems in Idaho add fluoride to the drinking water in a process known as fluoridation.

Fluoride Regulation

Fluoride has been shown to prevent tooth decay, but too much fluoride at an early age while the teeth are forming can cause discoloration and pitting of the teeth.  This condition is known as dental fluorosis. Overexposure to fluoride over a lifetime can lead to certain types of bone disease.

How Much Fluoride is Too Much?

EPA has set a maximum contaminant level (MCL) for fluoride of 4.0 mg/L for drinking water for community public water systems. (There is no drinking water standard for fluoride for noncommunity public water systems.) This means that some people who regularly consume water above this level can experience bone disease. EPA has also set a secondary standard of 2.0 mg/L. Children who regularly consume water above this level may experience dental fluorosis, ranging from white flecks in the mildest forms to brown stains and pitting in the most severe forms.

EPA recommends that children under 9 years old not consume water with fluoride concentrations higher than 2.0 mg/L on a regular basis. Your dentist can help you decide how much fluoride your family and you need.

The U.S. Department of Health and Human Services (HHS) recommends drinking water contain 0.7 mg/L of fluoride for optimal oral health. In 2017, EPA determined that a revision to the fluoride regulatory levels was not appropriate due to the low risk of fluoride at the current levels and higher priority contaminants. EPA will continue to monitor the evolving science, and, when appropriate, reconsider the fluoride regulatory levels.

Testing for Fluoride

Several methods are available to determine the general fluoride concentrations in your area:

  • If your water comes from a public water system, ask your water provider. If they are unable to locate the results, download them from the sample result tool on DEQ's website at
  • If you have a private well, have your water tested by a qualified laboratory to determine fluoride concentrations. Your local public health district can assist with testing your drinking water. Generally, follow the simple instructions and take a sample of water to a qualified laboratory for testing. Fluoride levels in drinking water can fluctuate naturally, so this sample may not represent a constant concentration.

If you have been advised by a professional that the concentration of fluoride in your drinking water is determined to be too high, it may be necessary to drink only bottled or properly treated water.

Reducing Fluoride in Your Drinking Water

Community water systems that exceed the MCL are required to reduce fluoride levels from drinking water. The best available technologies for control of fluoride in drinking water are reverse osmosis (RO) and activated alumina. Many other treatment options for fluoride removal exist including adsorptive media, chemical treatment, ion exchange, membrane separation, and an electrocoagulation process. All regulated public water systems must have a DEQ approved preliminary engineering report and DEQ approved plans and specifications prior to construction, modification, or installation of any drinking water treatment processes.

Home water treatment systems are also available for people looking to remove fluoride from their drinking water at home. The typical charcoal-based water filtration systems (e.g., Brita filters) do not remove fluoride from water. Boiling water also does not remove fluoride. Point-of-use distillation and reverse osmosis are treatment methods that have proven to be effective for removing fluoride. Only water used for drinking or cooking needs to be treated when fluoride concentrations exceed the MCL or secondary standard because fluoride is not absorbed through the skin. DEQ recommends ensuring all treatment system components and chemicals are certified by NSF. Always follow the manufacturer’s recommendations for operation and maintenance of any water treatment system. Occasional sampling from the treatment system is also recommended to determine the effectiveness of the treatment.

Staff Contacts

Drinking Water Bureau Chief
Tyler Fortunati
DEQ State Office
Water Quality Division
1410 N. Hilton
Boise, ID 83706
(208) 373-0140

DEQ Resources

Basic Information: Fluoride in Your Drinking Water

Labs Certified by Idaho to Perform Drinking Water Analyses

More Information

Questions and Answers About Fluoride

My Water's Fluoride
Learn the status of fluoridation in your water system.

Review of the Fluoride Drinking Water Regulation

Fluoride in Your Well Water

Fluoride & Fluoridation

Related Pages

Private Wells