Section 93(b) in The Punjab Capital (Development and Regulation) Building Rules, 1952
(b)be laid with a suitable fall and where practicable in a direct line. The standard gradient shall be 1 in 40 for a 10 cms. drain and 1 in 80 for a 15 cms. drain. The maximum and minimum gradients shall respectively be 1 in 20 and 1 in 80 for a 10 cms. drain and 1 in 40 and 1 in 140 respectively for a 15 cms. drain.
