In potable waters, the electrochemical corrosion of copper, the process of oxygen or chlorine reduction coupled with metal oxidation causes two major problems. First, corrosion is the driving force that causes the accumulation of copper oxidation products. These products are released into solution reaching the consumers' tap. Because of adverse effects of the copper on human health, their concentration is controlled. The Lead and Copper Rule establishes an action level for copper at 1.3 mg/L at 90th percentile for first-draw samples at the tap. Second, in a limited number of cases oxidation attack may be highly localized causing the formation of pits. Pitting attack may lead to a rapid perforation of the pipe wall and to the release of large amounts of corrosion products. In this paper, the authors present a consistent set of results clarifying the relationship between natural organic matter and the corrosion of copper.