Abstract: A high-pressure water pump for a pressure washer system includes an elliptical cam, a piston, and an unloader. The elliptical cam is designed to be powered by a prime mover, and is rotatable between a first orientation and a second orientation. The piston is designed to be driven within a chamber by the elliptical cam. During operation of the water pump, a flow of water enters the chamber through an inlet when the elliptical cam rotates to the first orientation. The flow of water exits the chamber at an increased pressure through an outlet when the elliptical cam rotates to the second orientation. The flow of water then exits the water pump through the unloader, which is designed to control pressure fluctuations in the flow of water, and is attached to the outlet of the chamber.