The utility model relates to a structure improvement of a civil water heater and the utility model comprises a cavity, wherein, a water outlet pipe with a valve, a water inlet pipe with a valve, a temperature controller and a power switch are arranged on the cavity; the water inlet pipe and the water outlet pipe are connected with a water storage tank which is provided with a water flow detector in the cavity. The utility model has the essential structure that a microwave heater is arranged in the cavity on the outer side of the water storage tank. The utility model has the characteristics of safe use, energy saving, simple manufacture, etc.