Abstract: A semiautomatic electronic system for sensing and accordingly raising if such is determined to be required, the fluid level of a liquid present in swimming pools, animal water drinking troughs, or any other liquid containment vessels. For the accomplishment of this task an electronic circuit periodically, in accordance with a schedule prescribe by a user, samples the environment of the space in a liquid containment vessel to determine if a liquid level has fallen below a predetermine level prescribed by the user. If such is the case, either a pump or a solenoid valve can be automatically activated, so as to cause liquid to be added to the containment vessel, only until the liquid in the containment vessel is restored to the required predetermined level.