Section 138(4) in Kolkata Municipal Corporation Building Rules, 2009
(4)The depth of the underground water reservoir/septic tank/inspection pits or manhole should not be more than the shallowest foundation depth and the distance between the edge of foundation and such underground structure should not be less than 50% of the width of the. underground structure provided however, this provision will not be applicable for such structures appearing at a distance of 4.0 m. or more from the main foundation line of the building.
