Our four year old borewell is 6 inch deep with 650 feet silt at the bottom, 25 feet pump and 5 HP air compressor water pipe. The static level of water is 600 feet. Till last summer we got good yielding from the borewell but then the yield had gone down to 5000- 7000 litres per hour, later to 3000 litres per day. In winters, the yield had gone up to almost 50 feet from ground but we faced another problem that the compressor was not pumping water. We got the compressor serviced and moved the water pipe level from 600 feet to 400 feet (when the yielding was 5000 litres per 2 hours). The problem got solved then but the water level has gone down again. Though we moved the pipe level to 600 feet but we are facing the same problem of water is not getting pumped at this level. Please tell what is the reason of this problem and how to solve this problem?