All water supply pipes or distributing pipes that are installed in the ground in any public way or other public place or in buildings, structures, or privately owned premises shall be covered to a minimum depth of not less than 5 feet (1525 mm) below the surface of the ground. No ashes, cinders, or refuse shall be used in back-filling any trenches or excavations in which water pipes are installed. All such pipes shall be coated with coal tar paint and insulated where they pass through concrete floors, or new concrete or masonry walls.