Influence of point-of-use dispensers on lead level assessment in drinking water of a lead pipe-free campus

Abstract

Point-of-use (POU) dispensers, referring to those directly connected to the water supply lines, are widely used in public facilities such as schools and universities in Taiwan. These dispensers are equipped with filters that can remove contaminants, including heavy metals in drinking water. Assessment of water lead (Pb) levels rely heavily on sampling surveys that involve various sampling protocols. This study evaluated the effects of using first draw (FD), flush (FL) incorporating at least 20 s of flushing, and random daytime (RDT) sampling protocols on Pb level assessment in water samples collected from faucets and POU dispensers of a Pb pipe-free campus between March 2017 and July 2020. This was the first study to examine the influence of POU dispensers on different sampling protocols and their survey results. Pb levels in 19% of faucet and 11% of dispenser samples exceeded the Taiwan EPA standard of 10 μg/L. FL sampling produced the lowest Pb levels, followed by RDT and FD in the samples collected from faucets. Interestingly, all three sampling protocols exhibited similar Pb levels in samples collected from dispensers. Thus, any of the three sampling protocols can be employed to monitor Pb levels in water samples collected from dispensers.