The impeller is the core component of a water pump; its primary function is to accelerate, draw in, and discharge the water flow. Its specific functions are as follows:

Accelerating water flow: As the impeller rotates, the vanes push the liquid outward, creating a radial flow pattern. A partial vacuum forms near the axis between the vanes and the shroud, drawing water in and accelerating it through the force of rotation.

Drawing in water flow: The rotation of the impeller creates a vacuum effect between the vanes and the shroud, drawing liquid into the pump. The liquid is then guided into the impeller, where it is accelerated and subsequently discharged.

Discharging water flow: The impeller discharges the water flow and generates water pressure. Higher water pressure and flow rates generally indicate higher impeller efficiency.