Galvanic corrosion after simulated small‐scale partial lead service line replacements

Abstract

Partial lead service line replacement with copper pipe creates a galvanic cell that can accelerate lead corrosion. Bench‐scale experiments under stagnant water conditions of high chloride‐to‐sulfate mass ratio (CSMR) demonstrated that galvanic connections between lead pipe (new or aged) and copper pipe increased lead release into the water by 1.1 to 16 times, compared with a full length of lead pipe alone. The extent of galvanic attack was dependent on drinking water quality. Exposure to water of high CSMR increased lead release in the lead–copper rigs by 3 to 12 times, compared with a lessaggressive low CSMR water. Galvanic current also increased by 1.5 to 2 times when switching from low to high CSMR. The small area of lead pipe adjacent to the copper joint (< 0.5 ft) dissipated 90–95% of the total galvanic current and accumulated a thick (1‐in.‐wide) layer of lead rust (i.e., a lead‐containing scale), which constituted a reservoir for semirandom particulate lead detachment into the water.