The invention discloses a water heater water tank. The water heater water tank comprises a hollow tank body provided with a cold water inlet and a hot water outlet, wherein at least one clapboard is arranged in the tank body; the clapboard is vertical to the rising direction of hot water; and water passing passages which communicate with an upper layer and a lower layer are formed in the clapboard. The invention further discloses a heat-pump water heater in which the water tank is provided with a perforated clapboard for layering arrangement; a water inlet pipe opening is provided with small holes; static heat-pump water heater condenser coils are arranged in a layered manner; the water inlet and the water outlet which are connected with a condenser in the circulation-type heat pump water heater are both arranged at a bottom layer, so that mixing speed of cold water and hot water is lowered, and a hot water utilization rate of a customer is improved; meanwhile, starting frequency of a heat pump is lowered; and heating speed is improved.