There are two different pump technologies used in water jet cleaning. The intensifier pumpmost is most popular, due to its higher pressure capability (up to 60,000 psi). An electric motor drives a hydraulic pump, creating oil pressure which drives the intensifier cylinders. The other pump type is positive displacement (PD). These pumps  work by an electric or diesel motor directly coupled to the reciprocating water pump pistons, and typically operate at lower pressures but have much higher water flow rates.