I sure am glad someone else tore the scab off of this old thread, since I had something I wanted to add but I didn't want to reopen an almost healed wound....
I was talking to my father a couple days ago about the work that they are doing in front of my parents house. The state recently purchased the land to do some drainage work and needed to find where some water pipes were and guess who they had come out and try to figure it out? A woman with a dowsing rods! Apparently her dowsing rods weren't ground balanced or bent properly since she was about ten feet off, but still not too bad.
So, I start telling my father about this thread and he tells me that my uncle and grandfather used to have "The Touch". My grandfather had a wrecking company here in Dutchess County until the 70s and they frequently would have to locate the water shut offs before they started knocking down the buildings. Apparently, they were pretty good at finding these using coat hangers, or something, I will have to ask my father for more information.
As far as the wrecking company goes, they used to tear down old churches, estates, mansions, homes, etc. I can not IMAGINE the detecting opportunities that they had.