Every vertical pipe shall be of such a diameter that-

a) the rate at which sewerage flows through such pipe at any point does nnot exceed the rate shown for the pipe of that diameter in column 2 or column 3 of Table VI, whichever is applicable; and

b) the rate at which sewage enter such pipe at any point (if the wetted portion of such pipe exceed two storeys in height above ground-floor level) does not exceed the rate shown for the pipe in column 4 of Table VI:

Provided that, wherever sewage enters any such pipe at two or more consecutive points, neither or none of which is more than 2,4 meters from any other, all the sewage entering the pipe at such two or more consecutive points, shall for this purpose of this paragraph, be deemed to enter such pipe at the lower or lowest of such two or consecutive points, as the case may be.