A new scenario of lead contamination in potable water distribution systems: Galvanic corrosion between lead and stainless steel.

Lead pipe has been banned for distributing drinking water in the 1980s and partial replacement of lead pipes with stainless steel pipes has been practiced in many Asian countries. Due to the different potentials of lead and stainless steel, galvanic corrosion may take place. The extent of lead release and effects of water chemistry on this process, however, are largely unknown. The objectives of this study are to characterize lead release resulting from galvanic connection between lead and stainless steel, the effects of pH, chloride and sulfate concentrations on this process, and the effectiveness of using orthophosphate to mitigate this problem. The experiments were conducted by connecting aged lead pipes to stainless steel fittings and placing the couple in different water conditions. The results of this study demonstrated that lead release significantly accelerated when lead and stainless steel were galvanically connected and the rate of lead release accelerated with decreasing pH and increasing chloride-to-sulfate mass ratio (CSMR). Orthophosphate could effectively reduce lead release but CSMR needs to be considered since water with a higher CSMR still caused more lead release when galvanic corrosion took place.