Metropolitan Water District to Begin Fluoridation of Treated Water Supplies

December 04, 2007

Beginning Oct. 29, the Metropolitan Water District of Southern California will join a majority of the nation's public water suppliers…

Beginning Oct. 29, the Metropolitan Water District of Southern California will join a majority of the nation’s public water suppliers in adding fluoride to its treated water supplies. Metropolitan’s treated water deliveries to San Diego County will be fluoridated starting Dec. 3 when fluoridation begins at the Skinner water treatment plant. Approximately half of the treated water used in the county comes from Metropolitan’s Skinner plant in southern Riverside County.

Fluoride is a naturally occurring mineral found in surface water (water from snowmelt, rivers and streams) as well as in groundwater. Fluoride helps teeth resist decay by strengthening the protective layer of tooth enamel and can reverse newly formed cavities. Fluoride has been added to U.S. drinking water supplies since 1945.

California Assembly Bill 733, signed into law by Governor Pete Wilson in 1995, authorized the California Department of Health Services to require water suppliers with 10,000 or more service connections or customers to fluoridate their public water supply. The California Fluoridation Regulations adopted by the California Department of Health Services were added to the California Code of Regulations (CCR – Title 22, Sections 64433 and 64434, pages 81to 87) in April 1998.

Metropolitan, although not required by law to fluoridate treated water supplies because it does not have direct connections to retail customers, decided to do so upon recommendations from the California Department of Public Health and the U.S. Centers for Disease Control and Prevention.

Naturally occurring fluoride levels range from 0.1 to 0.4 parts per million, and water in San Diego County is currently at 0.23 parts per million on average. With Metropolitan’s implementation of fluoridation, fluoride levels in San Diego county will be adjusted to the optimal range for dental health of 0.7 to 0.8 parts per million.

Any agency relying on the Water Authority for 100 percent of its treated water will receive fully optimized fluoride concentrations. If a water retail system blends Water Authority supplies with other non-fluoridated supplies, fluoride levels will be lower. Systems that receive no treated water from the Water Authority will have only natural levels of fluoride. A map showing a general representation of the Water Authority’s current estimate of fluoridation levels for member agencies can be viewed along with other fluoridation information on the Water Authority Web site at: The Water Authority’s Twin Oaks Valley Water Treatment Plant also is scheduled to deliver fluoridated water when it begins operations in April 2008.

Consumers can obtain information on the levels of fluoride that will be present in their water by contacting their retail water agency. A list of the Water Authority’s 24 retail member agencies is located at: Consumers with questions on whether they should adjust their dental health practices in any way should consult with their dentist.

Additional information on the fluoridation of drinking water is available on Metropolitan’s fluoridation Web page at: or by calling its Water Quality Information Hotline at (800) 354-4420; the American Dental Association:; the Centers for Disease Control and Prevention: and the California Department of Public Health: kingwater/pages/fluoridation.aspx.

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  • The San Diego County Water Authority sustains a $268 billion regional economy and the quality of life for 3.3 million residents through a multi-decade water supply diversification plan, major infrastructure investments and forward-thinking policies that promote fiscal and environmental responsibility. A public agency created in 1944, the Water Authority delivers wholesale water supplies to 23 retail water providers, including cities, special districts and a military base.

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