A lavatory unit in the form of a female urinal can be connected to any water supply. A timer valve (24) on the supply pipe (22) delivers a fixed volume of water to an overflow container (18). The water overflowing from the overflow container is delivered to the bowl (10) of the urinal by a network of pipes (20). In this way, the operation of the urinal is independent of the type of supply, and can be installed with minimal effort in a wide variety of locations.