I had this done when I lived in Idaho, and the person that did the dowsing had never done it before, and was not even familiar with the property. He read articles online on how it worked, and I think that he used a coat hanger; but he might have used a forked branch.
In any case, as we walked over the property, we could see the dowsing rod bending when we hit water, and were actually able to find several places that seemed like they would be a good prospect for a well.
After talking with my neighbors, we learned that there was a large underground river that ran through the property and some of the other nearby properties.
I could feel the dowsing rod moving when I tried it, although I did not seem to do as well as the friend who was actually doing the dowsing for me.
I think that it is something simple, maybe to do with magnetism between the minerals in the water, and in the dowsing rod, and it might make a difference with the magnetism of the person doing the dowsing.
My first husband could not wear a wrist watch because his body magnetism would literally stop the watch. When he got home from work, I would put on the watch (which was no longer running at all) , and soon it would start to work again. Whatever he had that stopped the watch, I had the opposite charge, and it would start the watch again.
I would wear the watch overnight, and the next day, he could wear it for a while until it stopped again during the day. Over the years, he had a lot of different watches, and they all did the same thing; so it was not just something erratic about the one watch.
Unfortunately, my daughter has the same electrical charge as her father, and she stops watches, and some of her other tech gadgets as well. So far, she said her Apple Watch is working fine though.