A water gun (10) is provided having a storage tank (18), a expandable pressure tank (19) having an elastic bladder (30) encased within an outer shell (29), and a pump (32) for conveying liquid from the storage tank to the expandable pressure tank. The conveyance of liquid into the expandable pressure tank causes the liquid to be pressurized by the biasing force of the elastic bladder. The pressurized liquid is released through a nozzle (21) coupled to the expandable pressure tank by actuation of a trigger (17).