Water safety is defined and determined by federal, state, and local
regulations. The main federal law that ensures the quality of Americans'
drinking water is the Safe Drinking Water Act (SDWA). Under SDWA, the
U.S. Environmental Protection Agency (EPA) sets standards for drinking
water quality and oversees the states, localities, and water suppliers
who implement those standards.
CDC promotes effective public health practices, such as community water
fluoridation. While it is not CDC’s responsibility to determine what
levels of fluoride in water are safe, our understanding about the safety
of fluoridation is guided by federal regulations, comprehensive reviews
conducted by expert panels, and individual studies.
Nearly all water on earth contains naturally occurring fluoride at
levels below, equal to, or above those used in community water
fluoridation. Investigation of the decay preventing effects of naturally
occurring fluoride in water led to the start of community water
fluoridation in 1945. For more than 60 years scientists have made
observations and conducted
epidemiological and animal studies to determine the effectiveness and
safety of fluoride in water.
- Scientific Reviews about
Water fluoridation has undergone extensive scientific review to
assess its public health benefits and risks. For many years, panels of
experts from different health and scientific fields have provided strong
evidence that water fluoridation is safe and effective.
Learn more about scientific reviews on
National Academy of Sciences on Fluoride in Drinking Water
The National Academy of Sciences, including its National Resource
Council (NRC), has considered the health effects of fluoride in
drinking water on several occasions. Additional information on the
NRC and its reports can be found on
National Academy of Sciences (NAS) on Fluoride in Drinking Water.
Additional information on the NRC report including a
Report in Brief *
and how to order
copies of the full report is available at
The proper amount of fluoride helps prevent and control dental caries
(tooth decay). Fluoride ingested during tooth development can also
result in a range changes in tooth enamel. Because fluorosis is a
condition that occurs when teeth are forming, only children aged 8 years
old or younger are at risk. Children older than eight, adolescents, and
adults are not susceptible to fluorosis.
Enamel fluorosis occurs among some people in all communities, even in
communities that do not fluoridate and have a low natural concentration
of fluoride in drinking water. All persons are encouraged to know what
steps can be taken to reduce the risk for enamel fluorosis.
The proper amount of fluoride at all stages of life helps prevent
and control tooth decay. Recent studies have raised the possibility
that mixing infant formula with fluoridated water, particularly for
infants exclusively on a formula diet during the first year of life,
may play a more important role in enamel fluorosis development than
was previously understood. Learn more about infant formula and
A study published by Bassin and colleagues suggests an
association between drinking fluoridated water and osteosarcoma in
adolescent males. The findings from a larger study on this
topic, conducted by the same institution, are expected soon. In making recommendations on
community water fluoridation, the CDC and the U.S. Public Health
Service are always guided by one overriding goal and interest—all
our recommendations are designed to protect the health and
well-being of the public. These recommendations are based on reviews
of the best available science. CDC continues to strongly support
community water fluoridation as a safe and effective public health
measure to prevent and control tooth decay and to improve overall
The safety of fluoride in drinking water at levels recommended for
preventing tooth decay has been affirmed by numerous scientific and
Scientists have found a lack of evidence to show an association
between water fluoridation and a negative impact on people, plants, or
Three additives—sodium fluoride, sodium fluorosilicate, and fluorosilicic acid—may be used to adjust the natural fluoride levels
in water to concentrations that prevent or reduce tooth decay. Learn
more about these additives and how they work in water.
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* Links to non-Federal organizations are
provided solely as a service to our users. Links do not constitute an
endorsement of any organization by CDC or the Federal Government, and none
should be inferred. The CDC is not responsible for the content of the individual
organization Web pages found at this link.
Date last reviewed: September 1, 2009
Date last modified: June 8, 2010
Division of Oral Health, National Center for Chronic Disease Prevention and