balance cu and inevitable impurities have been found to have conspicuously low dissolution rates of undesirable ions especially cu ions and other ions even in stagnant water and or at elevated temperature the alloys are desirably further contain up to 1 0 ca to further restrain dissolution of cu ions application_number US 2417879 A description in many developed countries water supply sources tend to be contaminated or deteriorated in water quality or purity by various causes as chemicals are added into the water in some water purification plants for the purpose of preserving the water quality this situation accelerates in turn the dissolution rate in water of an element or elements of the material of tubes for water supply giving rise to problems from the viewpoint of sanitation and preservation of water quality provision of a suitable material of tubes for water supply superior in reducing the dissolution rate in water of an element or elements thereof in workability and in saving of manufacturing cost has been urgently needed it is an object of the present invention to meet the aforementioned requirements for providing excellent tubes the present successful solution to these problems was arrived at after carrying out many time consuming experiments with respect to the dissolution rate of various elements into water under various conditions such as temperature and.