What are the factors responsible for pollution o the river?

the causes of water pollution are :

1. the toxic substances discharged 4m factories and industries make the water unfir 4 drinking.
2. marine habitat is affected by oil spills.
3. polluted water containing domestic sewage becomes a breeding ground 4 a number of water_borne diseases.weed
4. water contaminated with mercury is very harmful 4 all living beings.
5. smtymes ,too many weed and algae are seen growing in a water body. this is often a result of the chemicals which are used to gro crops,chemicals are carried by rainwater into water bodies.