Fluoride label concordance, pH, and electrical conductivity of commercial bottled waters in Ecuador

Background Bottled water is widely consumed, yet differing water sources and manufacturing processes may alter its physicochemical properties, with reported discrepancies between label declarations and laboratory analyses. Given the lack of regional evidence, this study aimed to determine the fluoride concentration, pH, electrical conductivity, and labeling concordance of commercial bottled waters in Ecuador. Methods Eighteen commercial bottled water brands in Ecuador were analyzed to determine fluoride concentration (mg/L), pH, and electrical conductivity (µS/cm). Differences across brands and associations among variables were evaluated using one-way ANOVA and Spearman rank correlation ( α = 0.05). Results Discrepancies between declared and laboratory-measured fluoride levels were identified in 10 brands (55.6%). Only two brands exhibited fluoride concentrations within the recommended range established by international health organizations (0.7–1.5 mg/L) for caries prevention: Omizu Sparkling (0.85 ± 0.07 mg/L) and Aki (1.45 ± 0.04 mg/L), with the latter approaching the maximum safety limit. Notably, Omizu Sparkling also presented the highest labeling discrepancy (325%). Physicochemical parameters differ significantly among brands across brands ( p < 0.01). Additionally, 50% of the brands evaluated exhibited pH values at or below the critical threshold for enamel demineralization (≤ 5.5). Electrical conductivity correlated positively with measured fluoride concentrations (r = 0.592, p < 0.001). Conclusions Bottled waters in Ecuador predominantly present sub-optimal fluoride levels and potentially erosive pH values. These findings highlight the need for stricter regulatory labeling enforcement and heightened clinical awareness among dental professionals.