XVIII. Every wash-basin, bath-tub, sink, urinal, water-closet, or other fixture -connected with the sewer-pipe of any building shall be separately trapped as close to the fixture as possible. Water-sealing traps of any pattern may be used when separate air-pipe connections from the top of the same are provided; where separate air-pipe connections are not provided, traps which will not unseal must be used. A trap will be considered as unsealed if, when syphoned, it shows a water-seal less than three-quarters of an inch in depth. This rule does not apply to traps of water-closets.

XIX. No overflow connection shall be made with any part of a trap. except into the inlet-pipe thereof, and above the body of the trap; and no connection of any waste-pipe - other than that from the fixture to be trapped - will be permitted to enter the body of the trap.