I have been using a borewell for the past 5 years. There has never been any problem in terms of the yield of this well, though it has declined very marginally (by about 10%) over the past 5 years. The concentration of dissolved solids has, however increased substantially from 300 ppm to 500 ppm. The borewell contractor suggests that we drill further in this borewell so that with increased depth, the salt concentration will reduce. Is this true? If yes, what could be the reason for this phenomenon?