AWWA WQTC69499

As part of AwwaRF Project 3018, the release of Pb from new faucets and new and used water meters was measured. Data were obtained for brass compositions, scale compositions, and water chemistry. Pb (or Bi) is present in these brasses as small "islands" of metal, whereas Cu and Zn are mixed in a solid solution. With time, the brass shows preferential loss of Zn relative to Cu. Lead releases from the faucets in 6 hour stagnation runs increased rather than decreased with time. This behavior is inconsistent with formation of passivating scale layers, but is consistent with progressive dezincification producing a porous surface layer through which Pb can diffuse more rapidly, or from which Pb particulates can be detached more readily with time. The rate of Pb release was found to correlate inversely with the Zn/Cu ratio of the brass. Includes 11 references, tables, figures.