A liquid storage unit 11 for a vehicle (Fig.1, 1), the liquid storage unit comprising: storage means 13 for storing a volume of liquid (Fig.3C, 31) wherein the storage means comprises at least one fixed floor member 17 and at least one moveable floor member 19. The storage unit comprises conduit means 21 arranged to allow liquid to flow from the storage means; and restoring means e.g. a spring or diaphragm 15 for providing a restoring force to the at least one moveable floor member to bias it towards a first position. The moveable floor member is arranged to move from the first position to a second position under the weight of liquid in the storage means and the restoring means is arranged to push the moveable floor member towards the first position as liquid is removed from the storage means. The liquid may be urea, windscreen wash, fuel or oil. The storage unit may have multiple moveable floor members.
