AWWA WQTC65804

Lead exposure at the tap is caused by dissolved and particulate lead. The concentration of dissolved and particulate lead at the tap is directly influenced by the conditions of sampling. Debris trapped by aerators can contain lead particulates from lead pipe surfaces and corroded solder. The relative influence of flow rate and the presence of aerators are not clearly understood, but under certain circumstances, reducing the flow rate during sampling and removing the aerator may reduce particulate lead in tap water samples. The impact of the sampling flow rate, flushing and the faucet aerator on dissolved and particulate lead concentrations was investigated. Using a profile sampling approach, the concentration of particulate and dissolved lead was measured as a function of flushing time and volumes. Elevated particulate lead was present only in some of the first draw samples taken with an aerator in place which corresponds to the water in the interior plumbing. No simple correlation was found between lead concentrations and flow rate. Stagnation time of 30 minutes in lead pipes had a significant impact on the lead concentration in the first draw and flowing tap water samples. Includes 7 references, tables, figures.