There is hereby adopted for the purpose of establishing minimum standards of design, materials and workmanship for all plumbing hereafter installed, altered or repaired and to establish methods of procedure within the limits of the City that certain plumbing code known as the "National Plumbing Code", being particularly the 1968 Copyright Edition thereof, and the whole thereof of which not less than three (3) copies have been and now are filed in the office of the Clerk, and the same are hereby adopted and incorporated as fully as if set out at length herein, and from the date on which this Chapter shall take effect, the provisions thereof shall be controlling in the installation, alteration or repairing of plumbing. (1971 Code)