Thermodynamic and electrochemical methods were used to derive fundamental information about the likely corrosion processes of copper pipes in high chloride-low carbonate mains water under conditions of varying temperature and solution composition. The thermodynamic aspects consider the possible reactions and the stability of the resulting products at 25-100°C by means of potential-pH and stability diagrams, based on the calculations of the free energy change, ΔGT0, of the reaction considered. These diagrams were constructed at ionic concentrations of chloride and bicarbonate ions corresponding to those found in the mains water in Perth, Western Australia. The reactions and products suggested by the potential-pH diagrams were verified experimentally, where possible, by cyclic voltammetry and potentiodynamic polarization. Further confirmation was made by analyzing some of the products formed, chemically or electrochemically, by an X-ray diffraction technique.