Role of Aluminosilicate deposits in Lead and Copper Corrosion

Aluminosilicates frequently deposit onto plumbing materials in distribution systems. Such solids were previously believed to provide some degree of corrosion protection to pipes—although at the expense of increased head loss, reduced flow, and consumer complaints related to postprecipitation. However, this work demonstrates that new copper and lead pipe sections did not benefit from the deposition of aluminosilicate solids. In fact, in most situations the presence of solids actually caused the release of more metal to drinking water compared with solutions without solids. Final pH played a key role in determining the extent of copper corrosion, and the aluminum deposits prevented increases in pH during stagnation through a buffering action.