Basically, it would have to come down to this. One, pure water is actualy an insulator, but I doubt the water in her basement was void of any mineral content. A high content would have made the water conductive and slide down the conductivity scale as the mineral content moves toward zero. Two, human skin is less conductive when we are colder and more when we are warmer. The skin's resistance to current flow varies from person to person and is inflenced by many factors connected with the bodies physical condition. Third, elctricity will seek the least resistive path to ground. I would say that your conclusion that her power distribution system "had a good ground" was spot on. Apparently, the combination of the water's conductivity level and her skin's restistance to current flow was greater than the path to ground through the equipment ground system. Stay safe brother.