Pitting corrosion of copper in waters with high pH and low alkalinity

Localized or pitting corrosion of copper pipes used in household plumbing is a problem for some homeowners. Extreme attack can lead to pinhole leaks that may result in water damage, mold growth, and costly repairs. The objective of this research was to better define the specific water quality conditions that support pitting corrosion. Pilot-scale pipe rig testing found that pitting corrosion occurred in waters with low chlorine concentrations and dissolved inorganic carbon (DIC) concentrations of 5 and 10 mg/L C (and possibly 25 mg/L Q and pH 9 water in the presence of chloride. Orthophosphate and increased DIC concentrations prevented the initiation of localized corrosion. Water suppliers considering changes in treatment and water sources can use this information to avoid conditions that support localized corrosion of copper.-MPM.