Abstract: The present invention provides systems and methods of dispensing liquids. In one embodiment, the system includes a pump with a removable pump module with at least one displacement piston and at least one piston valve. A motor and base assembly provides the supporting components of the pump, which can be used in environments where precise small volumes of ultra-pure liquids must be transferred from a reservoir to a point of use. The preferred embodiment of the system prevents contaminants and air bubbles from being introduced into the liquid to be dispensed by placing a filter across the discharge line downstream from the pump, and providing a separate drawback line for performing the drawback of the liquid in the dispensing nozzle.