(1) Except in the case of resealing-traps, the maximum depth of water-seal in all fittings-traps shall be 100 millimetres.

(2) For two-pipe system installations, the minimum depth of the water-seal in all fitting-traps shall be 40 millimetres for waste-water fittings and 50 millimetres for soil-water fittings.

(3) For one-pipe systems and single-stack systems, the minimum depth of water-seal shall be 75 millimetres for waste-water fittings, and 50 millimetres for soil-water fittings.

(4) Every trap of which the seal is not readily accessible shall be provided with a removable cleaning-eye of sufficient size protected by the water-seal, and every trap shall be self-cleansing.

(5) Traps which depend for their seal upon movable parts or inaccessible interior partitions shall not be used:

Provided that grease-traps may have integrally cast partitions or corrosion-resistant material.