What is the optimal fluoride concentration in drinking water?

• A. 0.7 ppm
• B. 1.0 ppm
• C. 0.5 ppm
• D. 1.5 ppm

Answer: (A)

Fluoride in drinking water is set at a level that protects teeth from decay while keeping the risk of dental fluorosis in check. The protective effect comes from fluoride helping enamel remineralize and resist acid attacks, especially during tooth development. The commonly recommended universal level is 0.7 mg/L (0.7 ppm) because it provides meaningful caries prevention across different climates and water consumption patterns while keeping fluorosis risk low for most populations. Higher concentrations, like 1.0 mg/L or more, offer little extra caries benefit but increase fluorosis risk; lower concentrations, such as 0.5 mg/L, reduce fluorosis risk but lessen caries protection. Therefore, 0.7 ppm is considered the optimal balance.