COMPARATIVE EVALUATION OF PHYSICOCHEMICAL AND QUALITY PARAMETERS OF COMMERCIAL DRINKING WATER

Abstract

Commercial drinking-water products vary significantly in terms of mineral content, treatment level, and physicochemical quality, and there is a need for systematic comparisons of different brands. During this study, 16 physicochemical parameters were comparatively analysed in eight anonymised commercial drinking-water brands, in purified, packaged, natural mineral and high-mineral packaged categories. Data were analysed using descriptive statistics, one-way analysis of variance, Tukey post hoc comparisons, Pearson correlation, principal component analysis, and hierarchical cluster analysis. Predefined limits were also applied to the selected quality indicators pH, TDS, turbidity, nitrate, fluoride, iron and lead. There were significant differences between brands for all measured parameters (p < 0.001) and effect sizes were very large. The mineral brands of purified water were found to have lower mineral content than that of the high mineral content brand of packaged water with electrical conductivity, total dissolved solids, hardness, alkalinity and major ions showing an increasing trend. High positive correlation was seen between conductivity and TDS, hardness and alkalinity, calcium and chloride, and calcium and sulphate. In total, 87.5% of the observations were within all of the screening limits. Every flagged observation was for brand H, primarily due to high total dissolved solids with some exceedances of fluoride and lead. The principal component and cluster analyses distinctly distinguished lower-, intermediate-, and higher-mineral water groups. These results reveal the high physicochemical variability between the commercial drinking water categories and justify the regular batch-wise monitoring, transparent labelling of the minerals and wider mineral monitoring.