A powder dispenser for a waste disposal system includes a mounting portion that is adapted to be secured to a waste disposal unit, and a container defining an interior space in which a powder such as sodium bicarbonate may be stored. The container is releasably mounted to the underside of a hinged lid member of the waste disposal unit. A directional dispensing system is provided for dispensing powder from the container into a targeted portion of the waste disposal system. The directional dispensing system is constructed and arranged to concentrate initial dispersal of the powder to a single side of the container and includes a dispensing orifice. The dispensing orifice is preferably oriented to limit initial dispersal of the powder within a defined angular range with respect to the longitudinal axis of the lid member, and is spaced axially and laterally with respect to the waste disposal unit at distances that facilitate distribution of the powder to desired targeted portions of the waste disposal unit. The container and waste disposal unit also define a venting path so that the powder within the container can also absorb odors within the waste disposal unit.