Abstract: A power cord grommet is provided having a compressible, reverse tapered portion that is insertable into the power cord opening of a sewage or sump basin cover and expandable therein when subjected to higher fluid pressures from within the sump basin so as to form a tighter seal against that opening. That expandability under higher fluid pressure is facilitated by a plurality of tapered recesses in the bottom surface of the grommet adjacent the reverse tapered portion. A hole is provided in the grommet to receive the power cord, and a slit is cut from the hole to the side of the grommet to allow the cord to be inserted into the hole.