2015 United States Public Health Service optimal fluoride level adherence and operation among adjusting water systems in 40 states: 2016–2021

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.