Question

what is sewage explain why it is harmful to discharge untreated sewage into rivers or seas ​

Answer 1

Sewage is the wastewater containing both liquid and solid wastes produced by human activities from homes, industries, hospitals, offices, etc. Sewage contains various contaminants including disease-causing bacteria and other microbes.

Answer 2

Sewage contain waste of both human and Industrial waste .human being waste such as excreta  and industrial waste as chemicals. discharge of sewage into rivers have seen harmful because it make them polluted