Lead release in drinking water resulting from galvanic corrosion in three-metal systems consisting of lead, copper and stainless steel

[Display omitted] •Stainless steel pipes are commonly used to replace lead pipes in Asia.•Three-metal galvanic system can form during partial replacement of lead pipes.•Lead release was the highest when materials were in order of reduction potential.•A more fluent electron transport resulted in more lead release.•The presence of a third metal can influence the magnitude of galvanic currents. Lead pipe has been banned in the drinking water distribution system in most countries since 1980s. Although water authorities around the world have attempted to replace all remaining lead pipes in service, pipe replacement was often hindered by high cost and lack of access to private premises. Hence, partial replacement has become a common scenario where portions of lead pipes remain in the system. When the lead pipe is connected to two other different metallic materials at both ends, two different galvanic couples can form simultaneously in this three-metal system. The release of lead resulting from galvanic corrosion in such three-metal systems consisting of lead (Pb), copper (Cu) and stainless steel (SS) with three different configurations, namely Cu-SS-Pb, SS-Cu-Pb and Cu-Pb-SS was investigated in this study. The results showed that when the materials are arranged in order of reduction potential as in SS-Cu-Pb configuration, lead release was the highest. A more fluent electron transport across the system was proposed based on the direction and magnitude of galvanic currents measured at each galvanic couple.