I am residing in Kottayam, Kerala. I have a borewell, 125 feet deep. It struck rock at 65 feet and we found water at 100 feet. Now it is 3 years old.  Details regarding the borewell are as follows: Diameter: 4 in, Depth: 125 feet from surface, Rock depth: 60 feet, Casing: PVC, Casing depth: 65 feet, Construction date: 01-02-2006, Pump: 1 HP compressor pump.

Recently we have noticed that the water is slightly muddy and carries small soft rock particles with it. The yield is poor. It gives approximately 250 litres of water in a hour.

My question is:
 1) Does the yield improve if I increase the depth to 225 feet? Or any other suggestions to increase the same?
 2) Why does the water become muddy and carry soft rock with it?
 3) Do borewells need periodic flushing?
 4) What is the optimum depth for using a compressor pump? 

Abba
abbiji@gmail.com