Abstract: The invention provides a device for reducing the volume of water flushed from a water closet. A rectilinear container has front, rear, side and bottom walls. An elongated suspension member has a hook at an upper end thereof for engaging the rim of the water closet and at its lower end it can engage bearing means on one of the rear or side walls of the container to suspend the container within the water closet. The volume of the container can be adjusted since one of the front or side walls has a lower fixed portion and an upper sliding portion, the sliding portion being vertically slidable relative to the fixed portion. The normal flush volume of the water closet is reduce by the volume of the container, thereby saving water.