(1) In respect of each dwelling-house, there shall be provided not less than one trapped dish-gully.

(2) Such gully shall be set on a base of concrete not less than 150 millimetres thick and having a composition not inferior to 50 kilograms of cement to 65 cubic decimetres of fine aggregate to 130 cubic decimetres of coarse aggregate, Grade 20.

(3) All such gullies, shall be encased in similar concrete to a thickness of not less than 100 millimetres, and dishing of internal dimensions not less than 400 millimetres by 450 millimetres or more than 900 millimetres by 600 millimetres shall be provided, which dish shall be at least 75 millimetres above ground-level and finished off smooth, and shall have a fall of at least 75 millimetres to the centre of the gully, and shall be surmounted with a kerb at least 75 millimetres high and 75 millimetres wide.

(4) Except where otherwise permitted by the local authority, the maximum distance from the ground-level to the top of the water-seal in all gullies shall not exceed 450 millimetres.