Division of Environmental and Community Health

Maine Center for Disease Control & Prevention

A Division of the Maine Department of Health and Human Services

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Fluoride & Fluoridation

Fluoride and Fluoridation


Fluoridation of drinking water is the addition or adjustment of fluoride to a drinking water supply for the purpose of preventing and controlling tooth decay.

Fluoride is voluntarily added to some drinking water systems as a public health measure for reducing the incidence of cavities among the treated population. The decision to fluoridate a water supply is made by the local municipality, and is not mandated by EPA or the State of Maine. The U.S. Centers for Disease Control and Prevention (CDC) provides recommendations about the optimal levels of fluoride in drinking water in order to prevent tooth decay.

There are 65 community water systems in Maine that currently fluoridate, providing drinking water to 133 communities throughout the state, to over 520,000 people.

Fluoride can also be present in water systems that do not fluoridate. Most water supplies contain some naturally occurring fluoride from the erosion of natural deposits in the bedrock. Fluoride can also enter drinking water as a result of impact to groundwater in discharge from fertilizer and aluminum factories from fertilizer.

Optimal Level and Recommended Control Range

The target level of fluoride for dental benefit is 0.7 milligrams per liter (mg/l) in drinking water in Maine. The recommended control range is 0.5 to 1.2 mg/l (parts per million) of the optimum level. The recommended control range helps maintain optimal fluoridation.


All public water systems that fluoridate must monitor and report the daily fluoride concentration at each application on days in which fluoride is added. Water systems that fluoridate must fill out and submit a Monthly Operating Report (MOR) to record and track the level of fluoride in their water system. These MORs must then be submitted to the Drinking Water Program on a monthly basis.

What is the Maximum Contaminant Level (MCL) for Fluoride?

The Environmental Protection agency (EPA) has established a Maximum Contaminant Level (MCL) for fluoride in drinking water at 4.0 ppm (milligrams per liter, mg/L).

What are the Health Effects of Fluoride?

Exposure to excessive consumption of fluoride over a lifetime may lead to increased likelihood of bone fractures in adults, and may result in effects on bone leading to pain and tenderness. Children aged 8 years and younger exposed to excessive amounts of fluoride have an increased chance of developing pits in the tooth enamel, along with a range of cosmetic effects to teeth.


As of February 29, 2012, the Rules Relating to Fluoridation of Public Water Systems were incorporated into 10-144 CMR 231, Section 4(J) of the State of Maine Rules Relating to Drinking Water.

Additional Resources