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Basic Information about Fluoride in Drinking Water

Fluoride at a Glance

Maximum Contaminant Level (MCL) = 4 milligrams per Liter (mg/L) or 4 parts per million (ppm)

Maximum Contaminant Level Goal (MCLG) = 4 mg/L or 4 ppm

Health Effects
Some people who drink water containing fluoride in excess of the MCL over many years could get bone disease (including pain and tenderness of the bones); children may get mottled teeth.

Drinking Water Health Advisories provide more information on health effects

Chemical Abstract Service Registry Number

Sources of Contamination
Water additive which promotes strong teeth; erosion of natural deposits; discharge from fertilizer and aluminum factories

List of all Regulated Contaminants (PDF) (6 pp, 396K, About PDF)

EPA regulates fluoride in drinking water to protect public health. Fluoride may cause health problems if present in public or private water supplies in amounts greater than the drinking water standard set by EPA.

What is fluoride?
Fluoride compounds are salts that form when the element, fluorine, combines with minerals in soil or rocks.

Uses for fluoride.
Many communities add fluoride to their drinking water to promote dental health.

If you are concerned about fluoride in a private well, please visit:

What are fluoride's health effects?
Some people who drink water containing fluoride well in excess of the maximum contaminant level (MCL) for many years could get bone disease (including pain and tenderness of the bones); children may get mottled teeth.

This health effects language is not intended to catalog all possible health effects for fluoride. Rather, it is intended to inform consumers of some of the possible health effects associated with fluoride in drinking water when the rule was finalized.

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What are EPA's drinking water regulations for fluoride?
In 1974, Congress passed the Safe Drinking Water Act. This law requires EPA to determine the level of contaminants in drinking water at which no adverse health effects are likely to occur. These non-enforceable health goals, based solely on possible health risks and exposure over a lifetime with an adequate margin of safety, are called maximum contaminant level goals (MCLG). Contaminants are any physical, chemical, biological or radiological substances or matter in water.

The MCLG for fluoride is 4 mg/L or 4 ppm. EPA has set this level of protection based on the best available science to prevent potential health problems. EPA has set an enforceable regulation for fluoride, called a maximum contaminant level (MCL), at 4 mg/L or 4 ppm. MCLs are set as close to the health goals as possible, considering cost, benefits and the ability of public water systems to detect and remove contaminants using suitable treatment technologies. In this case, the MCL equals the MCLG, because analytical methods or treatment technology do not pose any limitation.

EPA has also set a secondary standard (SMCL) for fluoride at 2 mg/L or 2 ppm. Secondary standards are non-enforceable guidelines regulating contaminants that may cause cosmetic effects (such as skin or tooth discoloration) or aesthetic effects (such as taste, odor, or color) in drinking water. EPA recommends secondary standards to water systems but does not require systems to comply. However, states may choose to adopt them as enforceable standards. Tooth discoloration and/or pitting is caused by excess fluoride exposures during the formative period prior to eruption of the teeth in children. The secondary standard of 2.0 mg/L is intended as a guideline for an upper boundary level in areas which have high levels of naturally occurring fluoride. It is not intended as a substitute for the lower concentrations (0.7 to 1.2 mg/L) which have been recommended for systems which add fluoride to their water. The level of the SMCL was set based upon a balancing of the beneficial effects of protection from tooth decay and the undesirable effects of excessive exposures leading to discoloration.

The Phase II Rule, the regulation for fluoride, became effective in 1992. The Safe Drinking Water Act requires EPA to periodically review the national primary drinking water regulation for each contaminant and revise the regulation, if appropriate. EPA reviewed fluoride as part of the Six Year Review and determined that the 4 mg/L or 4 ppm MCLG and 4 mg/L or 4 ppm MCL for fluoride are still protective of human health.

States may set more stringent drinking water MCLGs and MCLs for fluoride than EPA.

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How does fluoride get into my drinking water?
Some fluoride compounds, such as sodium fluoride and fluorosilicates, dissolve easily into ground water as it moves through gaps and pore spaces between rocks. Most water supplies contain some naturally occurring fluoride. Fluoride also enters drinking water in discharge from fertilizer or aluminum factories. Also, many communities add fluoride to their drinking water to promote dental health.

A federal law called the Emergency Planning and Community Right to Know Act (EPCRA) requires facilities in certain industries, which manufacture, process, or use significant amounts of toxic chemicals, to report annually on their releases of these chemicals. For more information on the uses and releases of chemicals in your state, contact the Community Right-to-Know Hotline: (800) 424-9346.

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How will I know if fluoride is in my drinking water?
When routine monitoring indicates that fluoride levels are above the MCL, your water supplier must take steps to reduce the amount of fluoride so that it is below that level. Water suppliers must notify their customers as soon as practical, but no later than 30 days after the system learns of the violation. Additional actions, such as providing alternative drinking water supplies, may be required to prevent serious risks to public health.

If your water comes from a household well, check with your health department or local water systems that use ground water for information on contaminants of concern in your area.

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How will fluoride be removed from my drinking water?
The following treatment method(s) have proven to be effective for removing fluoride to below 4 mg/L or 4 ppm: distillation or reverse osmosis.

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How do I learn more about my drinking water?
EPA strongly encourages people to learn more about their drinking water, and to support local efforts to protect the supply of safe drinking water and upgrade the community water system. Your water bill or telephone book's government listings are a good starting point for local information.

Contact your water utility. EPA requires all community water systems to prepare and deliver an annual consumer confidence report (CCR) (sometimes called a water quality report) for their customers by July 1 of each year. If your water provider is not a community water system, or if you have a private water supply, request a copy from a nearby community water system.

The CCR summarizes information regarding sources used (i.e., rivers, lakes, reservoirs, or aquifers), any detected contaminants, compliance and educational information.

Some water suppliers have posted their annual reports on EPA's Web site.

Other EPA Web sites

Other Federal Departments and Agencies

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