Various constituents of domestic sewage are:

(i) Solid wastes such as faecal matter, detergents etc. dissolved/suspended in water from the kitchen, toilets, bathrooms and laundry.

(ii) Harmful pathogens including disease causing microbes- bacteria, viruses, fungi etc.

(iii) Dissolved minerals such as phosphates, nitrates, sodium ions, ammonia etc.

Discharge of untreated sewage in water bodies leads to:

(i) Contamination of water in the water bodies with the faecal matter rendering it unfit for future usage.

(ii) Accumulation of various pathogens in the water bodies that can cause water borne diseases.

(iii) Increase in the Biological Oxygen Demand (BOD) of the water body thereby deteriorating the quality of water.

(iv) Excessive accumulations of minerals causes accelerated aging of the water bodies due to rapid growth of algae, called eutrophication.

(v) Negative impact on the flora and fauna of the particular water body. Number of fishes are found to be less in water bodies with high BOD.