Abstract: A dual action piston pump has a centrally disposed pump cylinder having a pump piston therein. A transition section is secured to each end of said pump cylinder through which the media being pumped passes while being pumped from and to a four way valve. A piston rod is connected to each side of said pump piston. Each piston rod passes through the side wall of the transition section and extends into a drive cylinder where it is connected to a drive piston. The drive pistons are driven by a motive fluid which may be hydraulic fluid. Each drive cylinder has a motive fluid connection adjacent to its distal and proximal ends so that both drive pistons can be driven in both directions. As the pump piston moves in one direction media is being pumped out on one side while media is being drawn in on the opposite side. The four way valve connects one side of the cylinder to a suction intake and the other side of the cylinder to the discharge. The valve reverses these connections when the stroke of the pistons reverse.