While your sump pump helps drain water out of damp areas, especially in lower levels of your home like the basement, a sump pump check valve is there to keep that water from flowing back down into the sump pit.
Without the valve, if the sump pump ever turns off, the water that’s left in the pipe could flow back into the pit. A functioning valve boosts your pump’s efficiency and protects your system by making sure the water moves in one direction only — away from the pit and your home.