In accordance with one embodiment of the present invention, there is provided a submersible pump that includes a pump housing forming a main compartment for receiving a pump impeller and having liquid entrance and exit openings in said main compartment, and an impeller mounted in the main compartment. The pump housing is adapted for submersion in a body of liquid whose level is to be controlled, and a sealed auxiliary compartment is formed as an integral part of the housing and located to be at least partially submerged in the liquid body. A drive motor is coupled to the impeller for rotating the impeller to eject liquid from the main compartment through the exit opening. An electric-field sensor is mounted in the sealed auxiliary compartment for detecting the elevation of the surface of the liquid body adjacent the sealed auxiliary compartment. At least one controllable switch is connected in the power supply line for controlling the supply of power to the drive motor, and the electric-field sensor is connected to the controllable switch for opening and closing the switch in response to changes in the detected elevation of the surface of the liquid body adjacent the outer surface of the sealed auxiliary compartment.