Section 70(5) in West Bengal Municipal (Building) Rules, 2007
(5)No kitchen, bathroom or water closet shall be permitted in any basement unless the sewer levels permit the same and there is no chance of back flow and flooding of sewerage. If permitted, such kitchen, bathroom or water closet shall be placed against an external wall of the basement, which shall also be the external wall of the building and shall be adequately lighted and ventilated. Detailed plans showing arrangement for drainage including pumping system shall be submitted in such cases.
