Why is a sump pump check valve important?

A check valve is the same diameter as the discharge pipe into which it fits and is usually a different color. A check valve should be installed in order to prevent pumped water in the discharge line from re-entering the sump pit when the device is turned off. Without this valve, the pump will have to work twice as hard to remove the same column of water, which causes unnecessary strain to the pump components. A check valve can also prevent the rare yet disturbing possibility that a discharge line connected to a stream or pond will back-siphon into the sump pit.