Corrosion of distribution piping and horne plumbing has been estirnated to cost the public water supply industry more than US $ 700 million per year. Two toxic metals that occur in tap water almost entirely because of corrosion are lead and cadmium.
Three other metals (Cu, Fe and Zn), usually present because of corrosion, cause staining of fixtures,
n1etallic taste or both. The toxic metals lead and cadmium can cause serious health problems 'when prese nt in quantities above the levels set by the National Interim Printary Drinking Water Regulation (NIPDWR). In order to minin1ize the adverse effects of corrosion, it might be suggested that corroison should be ccntrol1ed by deposition of a Ca CO3 films