Impact of plumbing age on copper levels in drinking water

Theory and practical experiences suggest that higher copper levels in drinking water tap samples are typically associated with newer plumbing systems, and levels decrease with increasing plumbing age. Past researchers have developed a conceptual model to explain the ‘aging effect’ founded in the proposed evolution of copper(II) corrosion by-products on the pipe surface, based on theoretical considerations, anecdotal evidence and some data. In this study, the impact of plumbing age on copper levels in tap water samples and the internal surface corrosion of copper plumbing were systematically evaluated in 16 buildings with plumbing ages ranging from less than one to 44 years, using solids analysis approaches including XPS and XRD. Copper levels decreased with plumbing age and supported theory. A mix of stable and relatively unstable scales appeared on pipes, including cupric hydroxide, cuprite and malachite, although no obvious trend in scale composition with age was noted.