The invention relates to a reservoir (1) for a throughfeed for liquid, such as a liquid pump (10), to be set into operation selectively, from and/or to a body of liquid (8) such as a pond, aquarium or bath, comprising: a container (2) for containing liquid and with an outlet (9) for connecting onto the throughfeed to the body of water; and a refill container (3) which, depending on the level of the liquid in the container (2), is movable reciprocally between a high position and at least one lower position, and which is connected to an inlet of the reservoir connected to the body of liquid (8), wherein the refill container (3) comprises an overflow (11) along which liquid flows from the refill container into the container (2) in the at least one lower position of the refill container (3).