Drinking Water_Content Page_Fluoride

Fluoride in Drinking Water

Fluoride has been added to drinking water since the 1940s to improve dental health by strengthening teeth and preventing or reducing cavities. Fluoride is an additive, meaning communities are not required to use fluoride in their water systems. Rather, communities decide on a local level whether to implement water fluoridation.

FAQs

Why is fluoride added to drinking water?

Close-up of a person smiling who is drinking a glass of water

The decision on whether to add fluoride to a public drinking water supply is made at the local municipal level. Fluoride can be naturally present in drinking water because of geological soil composition and bedrock. When fluoride is present in small levels or not at all, fluoride can be added in small, regulated amounts as a public health measure to promote dental health. Fluoridation is the process of adjusting the amount of fluoride in public drinking water supplies to the optimal level that promotes dental health. The process may include adding fluoride compounds, such as fluorosilicic acid, sodium fluoride or sodium fluorosilicate, to the selected public water supply.

How is fluoridation monitored?

When a public water system chooses to add fluoride, the Wisconsin Department of Natural Resources (DNR) regulates the fluoridation process through monitoring requirements and inspections. The DNR determines fluoride levels based on the Environmental Protection Agency’s Maximum Contaminant Level (EPA MCL) and the Wisconsin Department of Health Services (DHS) recommended levels for health protection. The DHS makes its recommendations based on expert advice and studies, which can include federal entities like the Centers for Disease Control and Prevention, the nation’s public health agency. Required Consumer Confidence Reports are available to residents to learn more about monitoring water quality for the previous year.

What is the optimal fluoride concentration level?

The EPA set a maximum contaminant level (MCL) for fluoride in drinking water of 4 milligrams per liter (mg/L). In addition, community water systems that fluoridate are responsible for establishing a program to maintain the fluoride concentration in their distribution system within the range of 0.6 to 0.8 mg/L, as recommended by the DHS for optimal dental benefits. Wisconsin’s public water systems are required to monitor and control fluoride levels to ensure compliance with these regulations to protect public health. The DNR helps these water systems adhere to regulations to prevent adverse health effects related to excessive fluoride consumption in drinking water.

Is fluoride in drinking water safe?

In Wisconsin, the recommended fluoride level to promote dental health is 0.7 mg/L. The DHS makes this recommendation based on the available studies and evaluating emerging evidence.

Information related to Food and Water Watch et al. v. United States Environmental Protection Agency et al. (September 2024):

National Toxicology Program:

Additional related links

Does my public water system add fluoride?

From the Drinking Water System Portal, search for your water system by name and select your system.

  • Scroll down to the link labeled "Treatment Processes" and select it
  • Search for "Fluoridation" in the filter box
  • Look at the "Treatment Ended" column. Systems that are currently fluoridating will have a statement saying "Ongoing." Systems that did fluoridate but no longer do will have a treatment end date. Systems that have never fluoridated will have nothing listed.