Water pollution is being caused by :
a. disposal of sewage (waste water) directly into water bodies.
b. direct release of industrial waste containing poisonous substances into nearby water bodies.
c. throwing of garbage and animal carcasses near and into water bodies.
d. bathing, washing, defecating near and into water bodies.
e. excessive fertilizers, pesticides and insecticides get washed off by rain and enter into water bodies.
f. accidental oil spills from oil tankers into oceans.
g. release of hot water by power plants into rivers (thermal pollution).