Fluoride is supplemented at Denver Water’s treatment plants only when the concentrations fall below the levels recommended by the U.S. Public Health Service (led by the U.S. surgeon general) and the Colorado Department of Public Health and Environment.

The target level for fluoride in Denver Water’s drinking water is 0.7 milligrams per liter. A milligram per liter is equivalent to one part per million, or one drop in 55 gallons of water, or one minute out of two years.

The cost of adding fluoride varies year to year and depends on the source water used, but it is less than $1 per million gallons.

In a final recommendation announced April 27, 2015, the U.S. Public Health Service (PHS) — in consultation with a federal, interagency panel of scientists from the Centers for Disease Control and Prevention (CDC), U.S. Environmental Protection Agency, National Institutes of Health, Food and Drug Administration, Agency for Healthcare Research and Quality, and U.S. Department of Agriculture — updated its recommendation for fluoride in drinking water. The agency set the recommended concentration of fluoride to 0.7 milligrams per liter.

This is the first change to the PHS’s recommendation on fluoride in nearly 50 years, and the Colorado Department of Public Health and Environment has followed suit. Fluoridation is supported by the CDC, Denver Public Health Department and Denver Health, Denver Environmental Health, Tri-County Health Department (Adams, Arapahoe, Douglas), Jefferson County Public Health, American Medical Association, American Dental Association, Colorado Dental Association, Colorado Academy of Pediatric Dentistry, Colorado Medical Society, and Colorado Academy of Family Physicians.

What does the federal update mean for Denver Water? Not much, as we’ve been targeting a fluoride concentration of 0.7 milligrams per liter in our water since this was first proposed in 2011. Our source water’s level of natural fluoridation is typically between 0.08 and 0.90 milligrams per liter, so our expert water quality managers supplement natural levels sparingly and only when necessary to reach the 0.7 milligrams per liter target.

On Aug. 26, 2015, the Denver Water Board of Water Commissioners approved a resolution upholding Denver Water's policy of adhering to the recommendations of major public health agencies, including the 2015 PHS fluoride guidelines, regarding community water fluoridation. The Board's decision was informed by presentations from experts with varied views, extensive written public comment and staff analysis on community water fluoridation in Denver Water's operations.

• Studies by the PHS and others established the cause-effect relationship between fluoridation and the prevention of tooth decay.
• The CDC and the CDPHE have established targets for the fluoride concentration in drinking water. In the past, the targets were based on the annual estimated consumption of drinking water (extrapolated from average air temperature data) over a five-year period. Both agencies endorse the use of supplemental fluoride in drinking water.
• The American Academy of Family Physicians has issued the following policy statement: “Fluoridation of public water supplies is a safe, economical, and effective measure to prevent dental caries” (tooth decay).
• Since 1950, the ADA, along with the USPHS, has continuously and unreservedly endorsed the optimal fluoridation of community water supplies as a safe and effective public health measure for the prevention of dental decay.
• The ADA’s policy on fluoridation is based on its continuing evaluation of the scientific research on the safety and effectiveness of fluoride. The association continues to reaffirm its support for water fluoridation and has strongly urged that its benefits be extended to communities served by public water systems.
• Today, fluoridation is the single most effective public health measure to prevent tooth decay and improve oral health over a lifetime.

Fluoride’s positive effect on dental health — particularly for children — was discovered in the early 1900s in Colorado Springs. Researchers found that while the high levels of naturally occurring fluoride in Colorado Springs’ drinking water caused fluorosis (a barely visible lacy white marking on tooth enamel), it also prevented cavities. Further study revealed an optimum level exists at which the most benefit and protection against tooth decay is realized while minimizing the risk of fluorosis.

Fluoride was first added to Denver's water in 1953, when Denver Water and the City of Denver's Department of Health and Hospitals entered into an agreement to fluoridate the water.