Set on AC volts, put one probe in the ground hole of an outlet (the round one). Put the other probe in the water. If you have it, heaters are the prime suspects. Unplug one device at a time until you find the culprit.
thanks for the reply, electricity is witchcraft and my ignorance in the field is holding me back a little in this hobby. I need a book or something before I burn the house down.