Community Water Fluoridation Frequently Asked Questions

Fluoride is a chemical ion of fluorine, which is the 13th most common element in the earth's crust. It is naturally found in almost all soil and water and many rocks. It is released into the environment when rocks or soil containing fluoride are dissolved by water. It can also be released from volcanic emissions or through man-made processes.

Fluoride combines with outer enamel tooth layers, preventing cavities by making teeth stronger and more resistant to decay. Almost all water contains some naturally occurring fluoride, but usually at levels too low to prevent cavities. Many communities add a small amount of fluoride to the water supply to prevent cavities and promote good oral health.

CDC does not mandate community water fluoridation. The U.S. Public Health Service (USPHS) recommended fluoride level is not an enforceable standard.

State and local governments decide whether to implement water fluoridation. Often, voters themselves make the decision to adjust water fluoride to improve public health. Some states have laws that require water systems of a certain size to provide fluoridated water. In some areas, the level of naturally occurring fluoride in water is already at a level proven to prevent cavities.

Fluoridated water and fluoride toothpaste work together to prevent cavities. Fluoridated water keeps a low level of fluoride in the mouth all day. Fluoride toothpaste provides a much higher concentration at important times of day (e.g., bedtime). Both types of fluoride strengthen the outer tooth enamel and slow the activity of bacteria that cause cavities. Together, the two sources offer more protection than using either one alone.

The best source of information on the fluoride level of your drinking water is your local water provider.

The fluoride content of well water can be determined only through laboratory analysis. Your local public health department can tell you where to have your home well water tested.

Drinking water needs to contain 0.7 mg/L of fluoride to reliably prevent cavities. If your drinking water contains less than 0.7 mg/L, speak to your dentist. If you have a child, you can also speak to your child's pediatrician. The dentist or pediatrician can discuss whether you or your child could benefit from other fluoride products.

The U.S. Environmental Protection Agency (EPA) recommends that drinking water contain no more than 2.0 mg/L of fluoride. This is a non-enforceable guideline and is intended to help children avoid dental fluorosis. This condition only develops in children while teeth are developing under the gums (up until about age 8).

When water fluoride levels exceed 2.0 mg/L, water systems are required to notify customers of the increased potential for dental fluorosis. Less than 1% of the U.S. population has water from private wells or drinking systems with fluoride higher than 2.0 mg/L.

EPA recommends that children 8 years and younger be provided with alternative sources of drinking water if their main source of water contains more than 2.0 mg/L of fluoride. Pregnant people or parents of children who live in areas with higher fluoride concentrations can use low-fluoride bottled water, for instance to mix infant formula.

If your water has a fluoride content of 4.0 mg/L or higher, contact your public health department for specific steps to follow. Consider using a filter that removes fluoride from water used for drinking or cooking. Fluoride is not absorbed through skin, so water with too much fluoride can still be used for cleaning and bathing.

Some, but not all, bottled water contains fluoride. Bottled water may come from a public water system that adds fluoride to improve oral health. It may also come from springs or aquifers where fluoride is naturally present.

Bottled water labeled as de-ionized, purified, demineralized, or distilled contain no or only trace amounts of fluoride, unless they specifically list fluoride as an added ingredient. Contact the bottled water’s manufacturer to ask about the fluoride content of a particular brand.

Getting enough water every day is important for your health. It prevents dehydration, a condition that can cause unclear thinking, result in mood change, cause your body to overheat, and lead to constipation and kidney stones.

If you drink mostly bottled water you may not get an optimal amount of fluoride to prevent cavities and promote oral health. Tell your dental provider if you drink mostly bottled water so they can help you find the best way to prevent cavities.

Formula that must be mixed with water (e.g., powdered or liquid concentrates) may increase the chance of dental fluorosis if it is a child's main source of food and if the water used to mix the formula is fluoridated. Ready-to-feed formula contains little fluoride and does not cause dental fluorosis.

If your child is only consuming infant formula mixed with fluoridated water, there may be an increased chance for mild dental fluorosis. Bottled water labeled as de-ionized, purified, demineralized, or distilled contains no or only trace amounts of fluoride, unless they specifically list fluoride as an added ingredient.

Parents can use low-fluoride bottled water some of the time to mix infant formula to lessen this risk. Look for bottles labeled as de-ionized, purified, demineralized, or distilled. Additionally, some bottled waters are marketed for infants and for the purpose of mixing with formula.

For more information, see the U.S. Food and Drug Administration's general Q&A about bottled water and infant formula.