vi. Water pollution occur when harmful substances like chemicals or microorganisms contaminate streams, revers, lakes and other water bodies.
vii. Causes of water pollution are: industrial wastes, oil pollution and acid rain.
viii. Contaminated water becomes unfit for consumption by humans and cattle. As the result, there is drastic reduction of the fish population. Water pollution results in increase case of water borne diseases like cholera, diarrhea, etc.
I hope this helps :)
