What is sewage? Explain why it is harmful to discharge untreated sewage into rivers or seas.

Sewage is a liquid containing wastes that is disposed of by households, industrial and agricultural activities in the water.

It is harmful to discharge untreated sewage into rivers or seas because it can pollute the whole source of water. Sewage contains harmful substances and disease-causing organisms. It is, therefore, dangerous to release untreated sewage into the water. 

[Extra information: Water cleaning is the process of eliminating all undesirable elements from water, like biological contaminants, dust, pollutants, dirt, etc.

Wastewater: Water from the kitchen used for washing dishes, etc. is known as wastewater.

Sewage: Wastewater released from homes, industries, hospitals and other public buildings is known as sewage. Sewage is the part of wastewater that is contaminated with feces or urine. These are carried off by sewers. There is an intricate system of sewers presents everywhere known as the sewer system.The process of wastewater treatment is known as sewage treatment.]