1. An automatic liquid-raising device with a storage tank (3) positioned above a closed working chamber (1), and a closed suction chamber (2) positioned above the storage tank (3) and having an outlet for liquid ; the working chamber (1) having a drain pipe (5) extending a certain distance downwards from its bottom and a suction-transfer pipe (7) rising from its top to the suction chamber (2) ; the storage tank (3) being connected through a charging pipe (6) to the working chamber (1) ; the suction chamber (2) having a feed pipe through which it aspirates liquid ; the charging pipe (6) having a valve (6a) for controlling the flow of liquid reaching the working chamber (1) from the storage tank (3) in dependence on the amount of liquid in the working chamber (1) ; the suction chamber (2) having a non-return valve (16) in its outlet (2a) for preventing return flow of liquid back into the suction chamber (2), characterised in that the storage tank (3) is mounted directly on top of the working chamber (1) and delivers working liquid through a charging pipe (6) to the top of the working chamber (1), the charging pipe (6) penetrating into the interior of the storage tank (3) ; the charging pipe (6) having a downwards-directed mouth (6a, 6a') cooperating with a valve plate (13, 23) actuated by a device (9, 12 or 24, 25) controlled by an actuator (9, 25) located in the working chamber (1) ; the actuator (9, 25) being connected to the valve plate (13, 23) through at least one sealed aperture (12, 24) in the separation wall (3a) between the storage tank (3) and the working chamber (1).