What is the current CDC-recommended optimal level of fluoride in community water fluoridation?

The U.S. Public Health Service (USPHS) updated the recommendation for optimal fluoride concentration in community water in 2015 to 0.7 mg/L (ppm). This single value replaced the previous range of 0.7-1.2 ppm, which was established when fluoride intake from other sources (toothpaste, dental products) was lower. The reduction to 0.7 ppm maintains caries-preventive benefits while reducing the risk of dental fluorosis (white spots on teeth). The CDC recognizes community water fluoridation at 0.7 ppm as one of the ten great public health achievements of the 20th century. Levels above 4 ppm are associated with skeletal fluorosis.