AWWA ACE54248

Copper is a commonly used material for water pipes, due to its resistance to corrosion relative to other plumbing materials. Corrosion of copper in drinking water still occurs under certain circumstances, however, with or without exposure to chlorine. The end result of copper corrosion is the release of copper ions into the water. Modeling copper dissolution is a difficult task, especially given the complexities of aged pipes. Some common relatively insoluble scales associated with copper corrosion include cuprite (Cu2O), malachite (Cu2(OH)2(CO3)), cuprous chloride (CuCl) and bronchanite (Cu4(OH)6(SO4)). As aresult of these complexities, minimal corrosion research has been done with aged pipes and the development of scale layers. In order to learn more about copper corrosion in real systems, both new and aged pipes were placed in a pilot apparatus in Hallam, Nebraska. The aged pipes were at least 30 years old and were from the basement of the community auditorium in Hallam. The pilot apparatus was located in the same room from which the aged pipes were removed. The Hallamcommunity water source is groundwater which undergoes no treatment or chlorination. The Nebraska Department of Health and Human Services has recorded only four times that temporary chlorination was used in Hallam for approximately 2 weeks in each instance: October, 1977, May, 1978, June, 1978 and October, 1987. This study had four objectives: to compare copper dissolution from aged (>30 years) copper pipe and new copper pipe when no corrosion control inhibitor is added; to determine the effect of chlorine addition to a previously unchlorinated drinking water distribution system with both aged and new copper pipes; to evaluate the change in dissolved copper concentration with different stagnation times and pipe ages; and, to compare these results with the results of other waters having somewhat different characteristics. Includes 5 references, table, figures.