Lead water pipes are a well-known source of dangerous lead contamination but partial replacement of the pipes can make the problem worse, U.S. researchers say. Lead pipes were once used routinely in municipal water distribution systems, but safety-minded lead-pipe-removal programs at water utilities across the country may be increasing the risk of lead exposure for water customers, researchers at Washington University in St. Louis said. Their research shows joining old lead pipes with new copper lines, using brass fittings, increases galvanic corrosion that can dramatically increase the amount of lead released into drinking water supplies, a university release said Thursday. This can happen if a utility company is replacing lead service lines but homeowners decline to have their sections of the lines replaced, researchers said. \"Work done in our laboratory shows galvanic corrosion in joined service lines is significant and lasts for a long time,\" researcher Dan Giammar said. Joined lead-copper pipe samples in his laboratory released five times as much lead as the original lead pipe did, he said.