Section 109(4) in Kolkata Municipal Corporation Building Rules, 2009
(4)Every bathroom or water closet shall -(a)be so situated that at least one of its walls shall face an interior open space or exterior open space or shaft and shall have an opening in the form at a window or ventilator or louvre not less than 0.40 sq. m. in area,(b)not be directly over any room other than a latrine or water closet or washing place or a bathroom or a terrace unless it has a water tight floor,(c)have the platform of seat made of water tight non-absorbent materials,(d)be enclosed by walls or partitions and the surface of every such wall or partition shall be finished with a smooth impervious material to a height of not less than 1 m. above the floor of such a room.(e)be provided with a door completely closing the entrance to it, and(f)be provided with an impervious floor sloping towards any drain with a suitable gradient.
