Evaluation of fluoride and calcium concentrations in drinking water from public water fountains on a university campus

Abstract

Optimal exposure to fluoride and calcium from tap water is beneficial for dental caries prevention. Water fountains may be an important source of drinking water in work and educational settings. The aims of this study were to quantify the fluoride and calcium concentrations of drinking water samples collected from public water fountains on the Indiana University-Purdue University Indianapolis campus; compare the fluoride and calcium concentrations in water collected at 2 different times; and determine whether the presence or absence of a visible external filter affects fluoride and calcium concentrations. Ninety samples were collected from 45 water fountains accessible to the public, and 90 duplicate samples were collected 1 month later. A fluoride ion-selective electrode was used in conjunction with an ion-specific meter to determine fluoride concentration, while atomic absorption spectrometry in an air-acetylene flame was implemented to quantify the calcium concentration. The fluoride and calcium concentration of drinking water samples displayed ranges of 0.62 mg/L to 0.97 mg/L and 56.61 mg/L to 89.11 mg/L, respectively. The concentrations of fluoride and calcium in drinking water were slightly lower at the second collection period (P < 0.001; Wilcoxon signed rank test). No statistically significant differences were observed in the fluoride or calcium concentration of drinking water collected from water fountains with an external filter cartridge in comparison with fountains that did not have a filter. Fluoride concentrations were within the optimal range recommended by the US Public Health Service for fluoridated drinking water, and calcium concentrations were consistent with those reported in previous surveillance studies