What could cause a pump to deliver less than its expected rate of discharge?

A clogged impeller can significantly restrict the flow of water through the pump, leading to a decreased discharge rate. The impeller is a key component that helps to move fluid through the pump, and when it becomes obstructed by debris or buildup, it cannot effectively transport the expected volume of fluid. This condition not only limits the output rate but can also result in increased energy consumption and potential damage to the pump over time.

The other factors, while they may influence pump performance, do not specifically relate to the immediate reduction of discharge caused by an obstruction directly within the pump's mechanism. A low power supply might affect the pump's ability to operate at all, rather than specifically causing a lower discharge flow. An incorrect pipe diameter could potentially create hydraulic inefficiencies but doesn't directly cause a clog in the impeller itself. Excessive vibration can indicate mechanical issues but is not a direct cause of reduced discharge rate; rather, it's a symptom of other potential problems.