There is a 10 volt current going though the water surply. I’ve checked the grounding of the apartment and everything looks good (the groud tester said it’s o.k.) Also the electric to the hot water heater was turned off. what else could it be?
Shalom, I could be a partial poor grounding wire from a low voltage source. Also when electrical wires are too close to piping you can get this kind of reading.