[commodor47]

To my knowledge there is no way to isolate the hot water tank from the rest of the water system unless the system has been modified to include a shut off valve either before or after the tank. It will fill when connected to city water and when operating the 12 volt pump (fills from the inside fresh water tank).

I have experienced what seemed to be a leak in the hot water tank but discovered it was just condensation forming between the outside tank wall and the insulation.

Dick