12. It must be laid in a straight line, if possible. All changes in direction must be made with curved pipes, and all connections with Y-branch pipes and one-eighth bends.
13. Any house-drain or house-sewer, put in and covered without due notice to the Health Department, must be uncovered for inspection at the direction of the inspector.
14. A running or half S-trap must be placed on the house-drain at an accessible point near the front of the house. This trap must be furnished with a hand-hole for convenience in cleaning, the cover of which must be properly fitted and made gas and air tight with some proper cement.
15. There must be an inlet for fresh air entering the drain just inside the trap, of at least four inches in diameter, leading to the outer air and opening at or near the street curb, or at a convenient place not less than ten feet from the nearest window. No cold-air box for a furnace shall be so placed that it can by any possibility draw air from this inlet-pipe. The inlet-pipe should never be carried up to the roof inside or outside the house.
16. No brick, sheet-metal, earthenware, or chimney-flue shall be used as a sewer-ventilator, nor to ventilate any trap, drain, soil, or waste pipe.
17. Every vertical soil-pipe and waste-pipe must be of iron, and, where it receives the discharge of fixtures on two or more floors, it must be extended at least two feet above the highest part of the roof or coping, of undiminished size, with a return bend or cowl. It must not open near a window, nor an air-shaft which ventilates livingrooms.
18. Soil, waste, and vent pipes, in an extension, must be extended above the roof of the main building, when otherwise they would open within twenty feet of the windows of the main house or the adjoining house.
19. Horizontal soil and waste pipes are prohibited.
20. The minimum diameter of soil-pipe permitted is four inches. A vertical waste-pipe, into which a line of kitchen-sinks discharge, must be at least two inches in diameter, with one inch and a half branches.
21. Where lead pipe is used to connect fixtures with vertical soil or waste pipes, or to connect traps with vertical vent-pipes, it must not be lighter than D-pipe.