You are here:
Mineralogical Evidence of Galvanic Corrosion in Domestic, Drinking Water Pipes
Citation:
DeSantis, M. K., M. M. Welch, AND M. R. SCHOCK. Mineralogical Evidence of Galvanic Corrosion in Domestic, Drinking Water Pipes. Presented at AWWA Water Quality Technology Conference, Seattle, WA, November 15 - 19, 2009.
Impact/Purpose:
To inform the public.
Description:
Drinking water distribution system (DWDS) piping contains numerous examples of galvanically-coupled metals (e.g., soldered copper pipe joints, copper-lead pipes joined during partial replacements of lead service lines). The possible role of galvanic corrosion in the release of lead or other metals has been a subject of debate for more than 25 years. Previously, the effects of galvanic corrosion on drinking water pipe materials have been studied by measuring electro-potentials across the galvanic couple1-3 or by examination of dissolved metal concentrations 4-6. These studies have generally been short-term, prohibiting the significant development of corrosion solids. This study presents the results of a visual and mineralogical characterization of scales developed over long time periods (up to 115 years) at galvanically-connected lead-brass and lead copper joints from several different drinking water distribution systems. The long-term exposure aspect of these samples allows: (1) a direct view as to which metal in the galvanic couple behaved anodically (i.e., corroded) over time, and (2) evaluation of mineral phases produced at these sites. Although beyond the scope of the current study, the latter observations, coupled with knowledge of the bulk water chemistry, may be used to model the conditions under which the deposits formed.
