A liquid dispenser uses a flexible bag having expansible and collapsible cells. A rigid manifold, and in one instance a rigid frame is provided in the bag to keep passages open in use and to isolate one of the cells from the remaining cells. The dispenser employs an efficient and quiet air pressure operating system. In one application, a concentrated drink mix may be held in a reservoir and diluted within other cells in the bag for dispensing to a cup or the like. A valve system allows for the particulates in the liquid without compromising the function of the valve.