We recently drilled a borewell - 6inch diameter and hit water at 340 feet. While drilling the borewell, there were small discoveries of water at 120 feet and also at 180 feet. We continued drilling upto a large water table was reached; which we hit at 340 feet.

A metal casing was installed upto 105 feet.

The borewell company now says that an inner casing (PVC) of 340 feet has to be laid to ensure that the borewell does not collape because of the gaps found at 120 feet and at 180 feet.

They claim that the casing will ensure long life of the borewell and safety of the motor. Since this is going to cost quite a bit of money, we would like to take an expert opinion if the casing is really required.

The borewell company also says that the inner casing has to be laid within a week's time of the initial drilling to avoid total collapse of the bore.

Please suggest!