It's not a case of "no scientific" explanation, which implies that it works but science cannot explain it. It simply doesn't work, though many insist otherwise.

Dowsing has been put to the test many times in controled environments and it fails. There is always some excuse for why it failed but always works in the field when skeptics are not around. Complicating matters, dowsers cannot even agree on what works (bent rods, peach saplings) or what can be located (water, pipes, wires, gold) or how it works (vibrations, magnetism).

Most dowsers would claim they can find copper wire, presumably because of some electrical field surrounding it, so let me suggest a test of this ability. Take ten 5-ft pieces of 2" PVC, with end caps, and insert into one a 4-ft length of heavy copper cable. That should set your coat hangers spinning. Do this while the test subject is some distance off and not able to watch. Other controls can be put in place to make sure this is done fairly. Then have the subject walk over the PVC pipes (no touching) and indicate which he thinks the copper cable is in. Repeat thirty times. We would expect three hits due to chance and can predict the likelihood of other outcomes. When put to this sort of test, most dowsers score about what chance would predict.

Summing up, dowsing relies on magical thinking and several biases to exist. If a driller refused to start on my place without witching first, I'd tell him to hit the road.