My father can do this. I have witnessed it. He can tell you where the water is and within a few feet how deep it is. He once got paid $100 to find buried water pipes on a job site.
The underground portion of a large job site had been completed years before and the drawings showing where everything was had been lost. The contractor who had performed the work had gone out of business. So no one had a clue where the water drain pipes and supply pipes had been terminated pending further development of the property.
My Dad told the GC he could tell him within a few feet the depth and location of every pipe on the property for $100. Because the pipes had water in them he was able to Dowse exactly where the pipes were laid and where the capped ends were and how deep they were. Doing this saved the General Contractor thousands of dollars he would have spent digging holes until he located them.
My Dad does this with two brass brazing rods and my Grandfather could do it with a forked limb from an orange tree.