Peter Morris, you may not call your fellow posters jerks outside the BBQ Pit forum. Further, you should not call your fellow posters liars without proof to back it up. Of course, you can correct someone if they’re mistaken, but being mistaken is not the same as lying. You know all this. Don’t let it happen again. You may consider this a warning.
Mind if I jump in on your challenge? Designing such a test is TRIVIAL. Here it is:
Find a field that’s going to be dug up & plowed. A quarter-section would be about right (that’s 1/2 mile by 1/2 mile).
Dig a trench across the field at some point and lay two pipes at the bottom. At one end, connect the pipes together. At the other end, put in a feed line and a circulating pump. Keep track of where the pipe is using a map or GPS coordinates or landmarks.
Bury the pipes and plow the field. Ideally, wait until a season’s worth of crops have been grown and replow the field, just to make sure you can’t see signs of the trench.
Fill the pipes and start the circulating pump. There is now water of any desired flow rate moving underground.
Tell the prospective dowser to wander the half of the field farthest from the feed line with five flags and plant them over the pipe.
If all five flags are planted within five feet of the pipe, then we have demonstrated that dowsing works.
If you’re concerned about the dowser being able to hear the water flowing in the pipes, then put them 8 feet down and either do the test on a windy day or make the dowser wear headphones pumping out white noise.
You continue to make that claim, but you’ve failed to back it up. It’s not obvious and it’s not proven.