I don't claim to know how this works, but it did, my son tried it, my coworkers tried it and it worked. I do not know about finding lakes underground streams, fresh, salt water, and the type of geological strata, but this method found water lines. I even set out a gallon bottle of water on the ground where I knew there was no other water, and as I crossed over the water bottle the wires deflected. I could not have squeezed the wires or deflected them in any way and it worked