A check valve assembly for a drain pump configured to transfer fluid from a sump, through a volute having a pump discharge passageway extending from the volute, includes a seat assembly and a flapper assembly. The seat assembly has a body with a first distal end and a second distal end, and a fluid passage extending through the body. The body defines a valve seat having a sealing surface about the fluid passage. The flapper assembly is operably coupled to the seat assembly. The flapper assembly has a moveable portion configured to selectively move between a closed position where the moveable portion seals against the sealing surface and an opened position where the moveable portion raises to allow liquid through the fluid passage. The check valve assembly is configured to be located within the pump discharge passageway.