The Influences of Storage and Further Purification on Residual Concentrations of Pharmaceuticals and Phthalate Esters in Drinking Water

The main objective of this study was to evaluate residuals from 28 pharmaceuticals and three phthalate esters (PAEs) in drinking waters, which were stored and further purified in different manners. Samples of drinking water from two different supply networks in Taiwan were collected in two batches from two research institutes (i.e., sampling sites N and S) in this study. Each batch of sampling was conducted on one Friday afternoon and the next Monday morning. Water storage tanks used in these two sampling sites are composed of different materials. Sampling points at each sampling site included one tap water pipeline, five water storage tanks, and five drinking fountains. It was found that retention of drinking water in the storage tanks over the weekend would be beneficial to spontaneous degradation of pharmaceuticals and PAEs. The preliminary results also showed that city water might have dissolved DiNP from modular water tanks made of fiberglass-reinforced plastics, whereas no such evidence was observed for water tanks made of stainless steel. Furthermore, a trace amount of pharmaceuticals and PAEs still could be detected in city waters, even in drinking fountain water.