AbstractIn this paper geophysical techniques, as used in ground‐water exploration are subdivided into “bore‐hole” and “surface” methods. The former include the commonly used electrical and gamma‐ray logging and the less commonly used hole calipering and current meter logging. Also included with this classification, but important enough to be considered separately, is the field of water‐level measurements. The surface techniques discussed include electrical resistivity and refraction seismograph exploration.Because of the type of data which they yield the surface methods are most economical where much area is to be explored and large quantities of water are needed. These factors limit the use of the techniques by small water well contractors in domestic water well work. These same contractors, on the other hand, can gain real economic advantages, in many cases, by use of one or more of the bore‐hole methods.Geophysical methods properly used can do much to guide the water well contractor. It is extremely important, however, that their use be carefully directed because in the past, where geophysical methods have failed, it has often been due to the incorrect application of the technique, rather than a failure