Must be stray voltage, you can check with a little gizmo you can get at Wally World for less than 2 bucks.Just follow 1journeymans advice and get a grounding probe and follow the directions. These can be pricey tho, all you need is a piece of good (aircraft quality) stainless steel wire. 1 end touching water anywhere in your sysyem and the other end on the screw that holds an electrical outlet in place-assuming your house hold wiring is grounded.