All private sewers from public sewer to the property line shall have an interior diameter of not less than six inches and inside the property line not less than four inches and shall be constructed of the best quality vitrified salt-glazed sewer pipe, with socket joints, made water-tight with Portland cement mortar. Every joint shall be cemented with mortar composed of one part of Portland cement and two parts of sand, and shall be dragged or swabbed while being laid so as to leave smooth and free from obstruction. Such private sewer shall be laid to the line and grade, and the inclination, where practicable, shall be not less than two feet to one hundred (100) feet. Private sewer shall, wherever possible, be connected with public sewer at wye junctions provided, but if necessary to break into a public sewer a joint must be taken out and a new joint wye junction inserted. (Prior code § 38-3-12)