Section 166(2) in West Bengal Municipal (Building) Rules, 2007
(2)(a)Proper slopes, not less than 1 : 60 shall be maintained all around a building for quick drainage of the entire plot as provided in this rule. Note.The possibilities of erosion or ground failure through ingress and percolation of water into soft ground or through joints and fissures in the soil crust shall be prevented by suitable surface protection measures such as surface grouting, stone pitching, planting of small plants and grass, so as to protect and make the surface impervious in accordance with the provisions of the BIS Codes, specially the minimum distance from provision required to be maintained for planting trees;(b)The flow of water, particularly on the upper side of the building, shall be diverted away from the foundations through suitable lined or unlined drains;(c)Drains for sullage or rain water must be constructed with round or half round tiles embedded in concrete, or with V-shaped stone masonry set in lime mortar and plastered over the inner surface with Portland cement, or with V-shaped stone concrete and the sectional area of every drain shall be subject to the approval of the Municipality;(d)Drains for surface water may be constructed only either of dry rubble masonry or of any other material approved by the Board of Councillors, and may be either rectangular or V-shaped in section. Such drains shall not be connected with any drain carrying sullage water or sewage;(e)Except with the written permission of the Board of Councillors, no covered drain shall be constructed and no existing open drain shall be covered in;(f)No building shall be placed to cover any drain;(g)Where a small drain is crossed by a private road, a removable R.C.C. slab cover or wooden grating or iron grating, if the Board of Councillors so direct, must be laid over the drain instead of a covered culvert.(h)Drains must discharge into the nearest water channel or public drain, unless in any case the Board of Councillors otherwise direct. The outfall of a drain into a water channel or public drain must be protected and guided in such manner as the Board of Councillors may direct. Where the drain of a private road joins the drain of a public road, the former drain must be so directed or so protected by strike-boards as to minimise the risk of damage to the public drain or road. Filters may also be provided where necessary;(i)Every building must be constructed so as not to project over, or admit of water from the roof falling upon or damaging any open space, road or passage it abuts, whether public or private;(j)Every building shall have rain water gutters and pipes connected to a drain along the periphery of a building;(k)A masonry drain must be placed round the periphery of every building or block of buildings, sufficient in section and slope to the satisfaction of the Municipality for the effectual drainage of the building and be placed as to admit the drainage being led into some drain at the time existing or projected;(l)The surrounding ground adjacent to the building must be sloped from all sides towards the perimeter drain and an impervious apron, not less than 0.75m wide, shall be provided all round the building to prevent the entry of water into the foundations.
