When we had a water main leak on a run of about 50m. Old iron main. Guy from Southeastern came out. He couldn't find it with whatever gizmo he had. East European lad, saying he shouldn't really do it as his bosses didn't believe in it, he dug out a set of divining rods. Saying he couldn't be sure he pinpointed a maybe about 10' from the actual leak. The leak was under concrete so I guess that might have skewed things. Not bad over 150' imo.