How expensive is it to set up a thumper and get back signals from a multitude of sampling points? Oil explorers do this, because the potential finds justify the expense. But a home well?? If the proposed well lies over reasonably homogenous horizontal strata, the water table below will be roughly between horizontal and parallel with the surface. Thus, generally, it will likely make little or no difference of one drills 50 feet over here versus 50 feet over there. (Well, no, don't drill from the top of the knoll.)

But the (essentially) random variation seduces some into believing they are really onto something. When someone does hit water soon, do they usually drill another hole nearby? But if they drill a long ways for nothing, and then try again not too far away, with better luck, do they ever ask why they missed the first time? Think about it.

I'd guess one reason no one does this is that it's too expensive, as Tornado has pointed out.

Well logging - Wikipedia, the free encyclopedia

Dowsing - Wikipedia, the free encyclopedia

Cost of equipment to log a well:$500,000.00 USD

Cost of equipment to witch: $0

You decide.