Question

there are 10 tube Wells in 50 houses which could be the long term impact on the water table​

Answer 1

If this happens then the the people of the fifty houses use the ten tube wells, then the water required by them is drawn from the ground. If these tube wells are used for long time, then the ground water would be reduced and the water table would go down.

The rainwater harvesting is

a method used to conserve water at the ground level for future use

Answer 2

The long term impact would be depletion of water table
I hope it helps you