What is the function of the pump? A pump is a device or machine that is used to move fluids from one place to another through a piping medium by adding energy to the fluid that is moved and continues continuously. And a pump operates with the principle of making a pressure difference between the suction and the discharge. In other words, the pump functions to change the mechanical power from a source of energy (propulsion) to kinetic energy (speed), where this energy is useful for flowing fluids and overcoming obstacles that exist throughout the drainage.