Which gauge casing pipe to be used?

Dear Sir,

This is Daniel from Chennai, I am in the requirement of drilling a new bore well for approx. 300ft . I am confused as to what gauge pipe to be used for casing because of the following reasons: 1. Neighbors have advised that 4 gauge pipes might not be able to withstand the pressure from earth and might collapse . 2. Bore-well contractor has advised that it is difficult for water to seep through 6 gauge pipes as soil may block slits I am confused which to go for, please could you kindly answer urgently as we are out of water. Your help is much appreciated,

Gratitude, Daniel