Finding a best suitable location for a borehole is similar to believing astrology, how ever this issue can be addressed by to ways one is scientific and the other is traditional method . In the earlier case it is identified by a probe pierced in to the soil in different locations and readings are taken . The later method is by the use of a coconut , not everyone can do this ! I personally experienced both the methods but I find coconut method is more fruitful identifying the right guy for this purpose is the key. Any way best of luck .....