Fluoride concentrations and pH levels of bottled mineral water commercially available in Bangkok, Thailand

Abstract

Objectives: To assess the fluoride concentrations and pH levels of commercially available bottled mineral water in Bangkok, Thailand.
Materials and Methods: Between April and June 2025, 41 brands of bottled mineral water were randomly purchased from retailers across Bangkok. Three bottles with different batch numbers were collected for each brand. Fluoride concentrations were analyzed using a fluoride ion-selective electrode with TISAB II, and pH levels were measured using a calibrated digital pH meter. Fluoride concentrations were compared among brands and among production batches within each brand using the Kruskal–Wallis test with Bonferroni-adjusted post hoc comparisons (α = 0.05).
Results: Fluoride concentrations varied widely among brands, ranging from 0.02 to 1.69 mg/L (p < 0.001).
No significant differences were observed among batches within any brand (p > 0.05). Thai-sourced mineral waters demonstrated the highest fluoride levels and the greatest variability, with four brands containing approximately 1.0 mg/L or higher. pH values ranged from 5.65 to 8.86, with most products falling within the recommended range of 6.5–8.5. Only one of the 41 brands reported fluoride content on its label.
Conclusions: Fluoride concentrations in bottled mineral waters sold in Bangkok show substantial variation, with several Thai-sourced brands exceeding recommended levels for tropical climates. The absence of fluoride labelling limits consumer awareness and complicates clinical assessment of total fluoride intake. Regular monitoring and improved labelling regulations are recommended to reduce the risk of excessive fluoride exposure, particularly in young children.