Water Fluoridation Basics
The mineral fluoride occurs naturally on earth and is released from rocks into the soil, water, and air. All water contains some fluoride. Usually, the fluoride level in water is not enough to prevent tooth decay; however, some groundwater and natural springs can have naturally high levels of fluoride.
Fluoride has been proven to protect teeth from decay. Bacteria in the mouth produce acid when a person eats sugary foods. This acid eats away minerals from the tooth’s surface, making the tooth weaker and increasing the chance of developing cavities. Fluoride helps to rebuild and strengthen the tooth’s surface, or enamel. Water fluoridation prevents tooth decay by providing frequent and consistent contact with low levels of fluoride. By keeping the tooth strong and solid, fluoride stops cavities from forming and can even rebuild the tooth’s surface.
Community water fluoridation is the process of adjusting the amount of fluoride in drinking water to a level recommended for preventing tooth decay.
Although other fluoride-containing products, such as toothpaste, mouth rinses, and dietary supplements are available and contribute to the prevention and control of tooth decay, community water fluoridation has been identified as the most cost-effective method of delivering fluoride to all, reducing tooth decay by 25% in children and adults.1
Fluoride benefits children and adults throughout their lives. For children younger than age 8, fluoride helps strengthen the adult (permanent) teeth that are developing under the gums. For adults, drinking water with fluoride supports tooth enamel, keeping teeth strong and healthy. The health benefits of fluoride include having:
- Fewer cavities.
- Less severe cavities.
- Less need for fillings and removing teeth.
- Less pain and suffering because of tooth decay.
In the 1930s, scientists examined the relationship between tooth decay in children and naturally occurring fluoride in drinking water. The study found that children who drank water with naturally high levels of fluoride had less tooth decay.2 This discovery was important because during that time most children and adults in the United States were affected by tooth decay. Many suffered from toothaches and painful extractions—often losing permanent teeth, including molars, even as teenagers.
After much scientific research, in 1945, the city of Grand Rapids, Michigan, was the first to add fluoride to its city water system in order to provide residents with the benefits of fluoride. This process of testing the water supply for fluoride and adjusting it to the right amount to prevent cavities is called community water fluoridation.
Since 1945, hundreds of cities have started community water fluoridation and in 2020, nearly 73% of the United States served by community water systems had access to fluoridated water. Because of its contribution to the dramatic decline in tooth decay over the past 75 years, CDC named community water fluoridation as 1 of 10 great public health achievements of the 20th century.
Community water fluoridation has been shown to save money, both for families and the health care system. The return on investment for community water fluoridation varies with size of the community, increasing as the community size increases. Community water fluoridation is cost-saving, even for small communities. The estimated return on investment for community water fluoridation (including productivity losses) ranged from $4 in small communities of 5,000 people or less, to $27 in large communities of 200,000 people or more.4
In 2020, community water systems that contain enough fluoride to protect teeth served more than 200 million people or nearly 73% of the US population. Because it is so beneficial, the United States has a national goal for 77% of Americans to have water with enough fluoride to prevent tooth decay by 2030.
Learn about CDC’s methodology for calculating fluoridation statistics.
Learn about the history and science behind water fluoridation, and how water fluoridation systems are implemented and operated in Fluoridation Learning Online, CDC’s free online training.
Learn more about fluoride and its role in oral health at the CDC podcast: Go With the Flow.
1 Griffin SO, Regnier E, Griffin PM, Huntley VN. Effectiveness of fluoride in preventing caries in adults. J Dent Res. 2007;86(5):410–414.
2 Dean HT. On the epidemiology of fluorine and dental caries. In: Gies WJ, ed. Fluorine in Dental Public Health. New York, NY: New York Institute of Clinical Oral Pathology., 1945:19–30.
3 Arnold FJ, Dean HT. Effect of fluoridated public water supply on dental caries prevalence. Public Health Rep. 1956;71:652–658.
4 Griffin SO, Jones K, Tomar SL. An economic evaluation of community water fluoridation. J Public Health Dent. 2001;61(2):78–86.