Abstract: Apparatus (10) is defined for regulating the level of liquid on a first side of a barrier (12) with respect to a moveable level of liquid on a second side of the barrier. The apparatus includes an inlet conduit (30) for positioning on the second side of the barrier and having an inlet (38) that is arranged for moving up and down with the liquid level, and an outlet conduit (16) for positioning on the first side of the barrier (12) and in liquid communication with the inlet conduit (30) across the barrier. The outlet conduit has an outlet (22) that can be located at a predetermined liquid level at the first side.