Most fridge filters are filled with carbon. Carbon takes out chlorine and taste and odor. If your on city water the carbon will do just that. Problem is, bacteria can live on the side of the filter that chlorine can't get to and it will multiply and start stinking. Carbon also polish's the water so the cubes look real clear. If you don't want to replace it, remove it like Redwood suggested and the cubes will be almost as clear as before and free of bacteria because the chlorine will be getting all the way to the cube.