Copper-Induced Metal Release from Lead Pipe into Drinking Water

The effect of added cupric ions (0 mg/L to 5 mg/L Cu⁺²) on possible deposition corrosion of lead pipe was investigated in bench-scale experiments under flowing and stagnant water conditions. Under stagnation the presence of cupric ions in the water feeding lead pipes marginally increased lead release into the water, but under continuous recirculation it could increase lead release by orders of magnitude. Other bench-scale experiments investigated galvanic corrosion between lead and copper pipes under stagnation, confirming that water chemistry (particularly the chloride-to-sulfate mass ratio [CSMR]) is a controlling factor in either “strengthening” galvanic corrosion and increasing water lead contamination by orders of magnitude (high CSMR water) or “weakening” the galvanic effect with less but still significant contribution to water lead contamination (low CSMR water). Longitudinal water pH measurements along the length of the galvanic rigs revealed a significant pH drop close to the lead:copper junction at relatively short stagnation times in high CSMR water, which is consistent with the observations of higher lead leaching and higher galvanic current measured in that situation.