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Fluoride is a naturally-occurring element found in soil and water. We add fluoride to Seattle drinking water to an optimal level for the prevention of tooth decay.
Fluoridation of Seattle’s water began in 1970 after a referendum vote in 1968 directed the City to fluoridate the drinking water. Seattle Public Utilities sells water to 21 wholesale customers (cities and water districts) generally located around Lake Washington. Those wholesale customers also receive fluoridated water. Nationwide, over 70 percent of people on public water supplies receive fluoridated water.
Public health, dental, and medical authorities overwhelmingly support drinking water fluoridation as safe and effective. Our local, state, and national public health agencies all strongly support fluoridation. The U.S. Centers for Disease Control have proclaimed drinking water fluoridation as one of the 10 great public health achievements of the 20th century. There is also strong support for water fluoridation by other prominent health organizations, including the American Dental Association, American Medical Association, and the American Public Health Association.
Seattle Public Utilities provides a fluoride level of 0.7 parts per million in the water. This level of fluoride began in May 2016, following a new recommendation from the federal Department of Health and Human Services (pdf) and new state requirements issued by the State Board of Health. From 1970 to 2011, the fluoride level was 1.0 parts per million. From 2011 to 2016, while the new federal recommendation was being reviewed and the state requirements were being updated, the fluoride level was 0.8 parts per million.