A liquid dispensing system generally includes a liquid pump connected to a source of pressure and an outlet tube. A first valve regulates the flow of pressurized air or gas between the source of pressure and the liquid pump. The first valve also regulates air or gas from the liquid pump to the atmosphere. A second valve may regulate the flow of liquid from the liquid pump through the outlet tube. A controller manipulates the first valve to create a pressure head in the liquid pump and then manipulates the second valve to dispense liquid. When dispensing is complete, the controller closes the second valve and manipulates the first valve to exhaust the pressure head from the liquid pump. An agitator resides in the liquid inside of the liquid pump. The agitator has a housing having a chamber for accepting an increased portion of the liquid in response to the creating of the pressure head and for rejecting such increased portion of the liquid from the chamber in response to the exhaustion of the pressure head. Liquid enters the chamber through an inlet tube and an intermediate tube controlled by a first check valve and exits the chamber through an intermediate tube and an outlet tube controlled by a second check valve.