Drinking water quality: Comparing inorganic components in bottled water and Italian tap water

This study reports an evaluation on the quality of drinking waters: 37 bottled water samples available in the market and 15 tap water samples supplied by municipal pipelines. Water samples were analyzed for 57 dissolved inorganic components. Considering the Italian and WHO guidelines for drinking water, results show an ample compliance with respect to the toxic elements Cr, Cd, Hg and Pb. In 20% of the bottled water samples, one or more components have been found at concentrations exceeding the Italian regulations (Cl(-), SO(4)(2-), NO(3)(-) limit for infants, F(-), As) and the WHO guidelines (B, U). These bottled waters are natural mineral waters, sometimes containing trace elements at concentrations significantly higher than those normally accepted in drinking water. With reference to the studied components, the overall quality of the investigated bottled waters does not appear to be always superior when compared with the municipal tap waters. Results indicate the need to update the current guidelines for drinking waters (including bottled waters) on the basis of epidemiological studies capable of assessing the toxicity related to long-term exposure to toxic and harmful trace elements. The mineral waters with excess concentrations of harmful elements should clearly report on the label the maximum daily uptake based on the lowest health risk exposure.