 The corrosion rate of copper in most potable waters is less than 2.5 µm/year, at this rate a 15 mm tube with a wall thickness of 0.7 mm would last for about 280 years.In some soft waters the general corrosion rate may increase to 12.5 µm/year, but even at this rate it would take over 50 years to perforate the same tube.Despite the reliability of copper and copper alloys, in some cold hard waters pits may form in the bore of a tube.