Question

find out from where the water comes into the tank and water excess water goes

Answer 1

the water come from groundwater with the help of motor in our tanks the waste we produce go into the river ,when water is access it may cause flood

Answer 2

The water come from groundwater with the help of motor in our tanks.

Through rains from the sky and the excess and the waste we produce to  go into the river.

When that water is access it may cause flood to the entire region and so proper dams should be constructed.