Ground water Level at Chennai - Ayanavaram

A better method for borewell

We have a bore depth of 300 feet and still did not have water in our area. We are planning a new bore.

What is the scientific method to find out the water level? Can you please suggest the best consultant in Chennai.

The other option we are planning is we have one more bore of 50feet depth, so can we go ahead and drill deeper to another 100ft and try this?

Which will be a cheaper method, kindly suggest.

Many thanks in advance,