In 2015, the United States Public Health Service (USPHS) set a target fluoride level for drinking water at 0.7 mg/L to maximize oral health benefits while minimizing any potential harms. Using water fluoridation operational data reported by water systems to the Centers for Disease Control and Prevention (CDC) Water Fluoridation Reporting System (WFRS) during 2016–2021, this study assesses how water systems performed around this target. The authors summarize completeness of data reporting, assess the distribution of monthly average fluoride readings (MAFR) values, and evaluate precision in maintaining fluoride levels. About 69% of adjusting systems provided data, with an average completeness of 63.8% among them. MAFR mean was 0.71 mg/L (SD: 0.20 mg/L), indicating that water systems have primarily adopted the USPHS target. About 76% of MAFRs fell ± 0.1 mg/L around the reporting system point's mean, indicating feasibility in maintaining precision around a target. State programs and water systems could work together to improve data quality and educate operators on best practices. Published 2024. This article is a U.S. Government work and is in the public domain in the USA.

Drinking water fluoridated at the level recommended by the U.S. Public Health Service (USPHS) reduces dental caries (cavities) by approximately 25% in children and adults (1). USPHS recommends fluoride levels to achieve oral health benefits and minimize risks associated with excess fluoride exposure. To provide the benefits of community water fluoridation, water systems should target a level of 0.7 mg/L and maintain levels ≥0.6 mg/L (2). The Environmental Protection Agency (EPA) sets a safety standard at 2.0 mg/L to prevent mild or moderate dental fluorosis, a condition that causes changes in the appearance of tooth enamel caused by hypermineralization resulting from excess fluoride intake during tooth-forming years (i.e., before age 8 years). During 2016-2021, fluoride measurements for 16.3% of population-weighted monthly fluoride measurements (person-months) reported by community water systems to CDC's Water Fluoridation Reporting System (WFRS) were <0.6 mg/L; only 0.01% of person-months exceeded 2.0 mg/L. More than 80% of population-weighted fluoride measurements from community water systems reporting to WFRS were above 0.6 mg/L. Although 0.7 mg/L is the recommended optimal level, ≥0.6 mg/L is still effective for the prevention of caries. A total of 4,080 community water systems safely fluoridated water 99.99% of the time with levels below the secondary safety standard of 2.0 mg/L. Water systems are encouraged to work with their state programs to report their fluoride data into WFRS and meet USPHS recommendations to provide the full benefit of fluoridation for caries prevention.