Experimental investigation of lead release during connection of lead and copper pipes

The release of lead from the pipes used as service lines for drinking water distribution can contribute to elevated lead concentrations in tap water. Several utilities are implementing lead service line replacement programs to mitigate high lead levels, and often utilities also replace service lines during public water main replacement or repairing a leak that affects the service line. Often only partial lead service line replacements can be completed because the utility does not have ownership over the entire service line and the property owner chooses to not replace their portion of the line. The connection of a new copper pipe or tube to the remaining section of lead pipe creates an electrical dissimilar metal connection that has been postulated to result in galvanic corrosion and an increase in release of lead into the water. The effects of coupling type and water chemistry on lead release were investigated in a set of laboratory-scale experiments with lead-copper assemblies. Experiments are being performed with sections of lead pipes provided by two utilities that have current lead service line replacement programs. The lead pipes are first reconditioned with water of similar composition to that in the utilities' distribution systems, and once lead concentrations stabilize the lead pipes are connected to copper tubing. The lead pipes and copper tubing are connected by three different methods: brass compression fitting, brass dielectric compression fitting, and a plastic fitting. Lead release is examined at both flowing conditions and following periods of stagnation. Experiments have been conducted with a laboratory system that includes recirculating flow and also with a set of pipe runs receiving once-through flow with water from one of the participating utilities. 2011