Frequently Asked Questions

Tooth decay is caused by bacteria in the mouth. When a person eats sugar or other refined carbohydrates, these bacteria produce acid that removes minerals from the surface of the tooth, a process known as demineralization. If demineralization goes on long enough, a cavity forms. Fluoride can promote the remineralization of enamel, preventing the cavity from continuing to form. Fluoride also reduces the ability of oral bacteria to produce acid.

Community water fluoridation is the adjustment of the fluoride concentration in the community water supply to a level that helps reduce tooth decay and promote good oral health. Fluoride is essential for strong, healthy teeth that resist decay. Almost all water contains some naturally occurring fluoride, but usually at levels too low to prevent decay. The optimum concentration of fluoride in water has been determined to be between 0.7 and 1.2 milligrams per liter (mg/L), depending on the air temperature in a given region. Given the dramatic decline in tooth decay over the past 60 years, the Centers for Disease Control and Prevention (CDC) named water fluoridation one of the Ten Great Public Health Interventions of the 20th Century, and it has been recommended by the past five U.S. Surgeons General.

The EPA establishes criteria for safe drinking water under the Safe Drinking Water Act and its amendments (1974, 1986 and 1996). These standards include the maximum contaminant level goal (MCLG), the maximum contaminant level (MCL) and the secondary maximum contaminant level (SMCL). The MCLG is a non-enforceable health goal set at a concentration to minimize adverse health effects. The MCL is an enforceable regulatory standard set as close to the MCLG as practical, taking into account factors such as treatment technology and costs. The SMCL is a non-enforceable secondary standard that, for fluoride, provides guidance on cosmetic considerations related to tooth enamel fluorosis. In 1986, the EPA established an MCLG and MCL for fluoride of 4 mg/L and an SMCL of 2 mg/L. The Safe Drinking Water Act requires periodic reassessment of drinking water regulations.