A venting system of a manually operated trigger sprayer vents the interior of a liquid container connected to the trigger sprayer. The trigger sprayer is provided with a vent chamber that surrounds the pump chamber, and a vent piston that surrounds the pump piston. The vent piston is received in the vent chamber for reciprocating movements with the pump piston in the pump chamber. The reciprocating movement of the vent piston alternatively opens the vent chamber to the exterior environment of the trigger sprayer and thereby vents the interior of the liquid container connected to the trigger sprayer, and closes the vent chamber thereby sealing the interior of the liquid container from the exterior environment.
