Section 399(21) in The Punjab Municipal Corporation Act, 1976
(21)the elimination from trade effluent, before it enters a municipal drain, of any constituent which in the opinion of the Corporation would, either alone or in combination with any matter with which it is likely to come into contact while passing through municipal drains, injure or obstruct those drains or make specially difficult or expensive the treatment or disposal of the sewage from those drains ;
