Abstract: In assembly for dispensing agents into drains and the like, includes a retaining member having a perforate wall structure substantially surrounding and enclosing a quantity of a sanitizing agent therein. The retaining member is preferably flexible and tubular, and may be formed into a donut-shaped configuration. The retaining member may be provided of a mesh material. The mesh initially holds the sanitizing agent, provided as a powder or in granular form therein. Upon wetting of the sanitizing agent, it may assume a gel-like consistency and erode to dispense the sanitizing agent into the liquid passing through the retaining member. A mount may be employed to both hold the retaining member in a proper position and configuration, and to secure edges of the retaining member in a closed position.