Described is a multi-function device for attachment to the tank of a toilet fixture. The multi-function device provides a diffusible air-treatment concentrate for deodorizing or otherwise treating the ambient air surrounding the toilet. At the same time, the multi-function device provides a water-soluble water-treatment concentrate for treating the flush water stored in the toilet tank. The multi-function device has a bellows with a varying cross-sectional area to provide, during a flush cycle, a variable flow of air over the air treatment concentrate and into the air.