The Process and Water Quality Specialists
Both lead and copper are ordinarily pretty resistant to corrosion. Nevertheless water is the universal solvent, and so long as these two metals continue to be used in water supplies there will be some lead and copper in the water exposed to them. EPA's Lead and Copper Rule (LCR) doesn't directly address corrosion, rather it addresses the presence of lead and copper in tap water. Controlling the appearance of lead and copper in solution isn't just a question of controlling corrosion. In fact, often, the corrosion of copper and lead does not result in the introduction of metal ions directly in solution, rather, it results in the formation of oxide, carbonate, or hydroxycarbonate scales on the metal surface. Thus the presence of lead or copper in solution is not just a question of corrosion, but also the solubility of these scales. Figure 1 illustrates many of the processes that influence the concentration of a corroding metal in solution.
Where lead is concerned small particulates of scale are also sometimes released, particularly if something occurs to disturb the surface of lead pipe.