Question

why is potassium permanganate is used during cleaning water tanks

Answer 1

Potassium permanganate is a point-of-entry treatment method that oxidizes dissolved iron, manganese, and hydrogen sulfide into solid particles that are filtered out of the water. It can also be used to control iron bacteria growth in wells and tanks.
I am not sure but I hope that it helps

Answer 2

Explanation:

Potassium permanganate is a very strong oxidizing agent. So, it helps in the oxidation of dissolved iron, manganese, and hydrogen sulfide.

Upon oxidation these get converted into solid particles which can be easily filtered out of the water.

Potassium permanganate also heps in controlling the growth of iron bacteria.

Therefore, due to these reasons potassium permanganate is used during cleaning water tanks.