This invention relates to a toilet bowl sealing device or assembly for use with floor closet flanges when capped upon the sewer drain pipe to which the toilet bowl is attached so that gas and water leakage is prevented. A plastic sealing ring is used that has both external and internal tapered sealing seats, the internal seat for a corresponding tapered seat in the depending sleeve portion of the closet flange and the internal tapered seat for receiving a corresponding external tapered seat on a centering funnel adapted to be rigidly adhered to the bottom surface of the toilet bowl about its discharge outlet and used in re-assembling the toilet bowl upon the floor closet flange after inspection or replacement of a sealing ring.