Section 128 in West Bengal Municipal (Building) Rules, 2007
128. Rain-water pipes.
(1) Rain-water pipe shall be least 75 millimetres (3 inches) in diameter and be constructed of cast-iron, wrought-iron, PVC glazed stoneware, asbestos or other equally suitable materials and shall be securely fixed.(2)The mode of drainage of rain water shall be as approved by the Authority.(3)The drainage from the roof and compounds paved or un-paved, will be permitted to flow over footpath into the kerb drains and ultimately into gully pits. Drainage from roof or compound, paved or un-paved, must not discharge into or be connected with any soil pipe or soil ventilation pipe or any waste ventilating pipe nor shall it discharge into sewer.
