Section 61(5) in Haryana Urban Development Authority (Erection of Buildings) Regulations, 1979
(5)Where the water closet discharges into a soil pipe which also receives discharge from another water closet, the trap of the water closet shall be ventilated by a pipe which shall :(a)have an internal diameter of not less than 50 cm.(b)be connected with the arm of the soil pipe at point not less than 7.5 cm and not more than 30 cm from the highest part of the trap, on that side of the water seal which is nearer to the soil pipe and in the direction of the flow; and(c)either have an open and as high as the top of soil pipe at or be carried into a soil pipe at a point not less than 2.0 metre above the highest connection to the soil pipe.
