Was he drilling in fractured rock or did he hit an impervious clay layer that was thinner at the 100’ well location?
My property is in the hills, at the very front of it is a road and on the other side of it is a river valley. The hills are stone, most people have cisterns instead of wells because you will NOT hit water no matter how deep you drill. I pump my water back from the well 8/10 mile to my house, it was either that or pull it from our lake, and that didn't excite me at all. I can go on the other side of the road and hit water with a hand drilled well, once on our side you have a short apron that might or might not produce but beyond that, you will get nothing. A whole lot of money changes hands when the property can support a well, so people make sure before they list it and if its there, they would find it because we don't have rural water this far out.