A watertight, multi-sectioned, sump-pump basin cover back-up device made of a first cover section defining an outer-rim having a central aperture for accepting a water tightly sealable second cover section having at least one opening therethrough for accepting a water-tightly sealable discharge pipe, another water-tight, uncoverable, covered aperture for drainage of water from the floor adjacent to the sump-pump basin into the basin only when the water-tight cover is removed, and an auxiliary discharge pipe having a predetermined height, providing for said pipe to function as a relief valve. The device fixedly or detachably attachable to a sump pump basin rim, reducing or eliminating sump-pump cavity overflow flooding, while retarding the escape of pump noise, odor, and gases known to emanate from sump-pump basins.