The invention relates to a water storage type heat pump water heater, including a compressor, a heat exchange coil, an expansion valve, an evaporator, a closed tank equipped with an intake pipe and a rising pipe and positive and negative electrodes insulated with each other, which are circularly connected in turn, wherein the heat exchange coil comprises an inner pipe containing heat pump cycle fluid and an outer pipe sleeved on the inner pipe, the outer wall of the inner pipe and the inner wall of the outer pipe are closely jointed, at least one channel which connects ports at two ends of the outer pipe is embraced between the outer wall of the inner pipe and the inner wall of the outer pipe, a channel outlet is embraced between at least one end of the ports at two ends of the outer pipe and the outer wall of the inner pipe, and the port comprising the channel outlet is positioned at one side outside a water tank at the joint part between the heat exchange coil while being mounted and the hot water tank; and the positive and negative electrodes are arranged at a position where the electrodes can contact with the effluent passing the channel outlet. The invention can give an alarm immediately when the outer pipe of the heat exchange coil is corroded and penetrated, reliably prevent the cycle fluid in the water heater from leaking into the water tank of the water heater as the heat exchange coil is corroded and penetrated, avoid water pollution of the water tank, and have timely, simple and reliable alarming mode.