With Torus Filtered Water Bowl Replacement Filters， you’ll have a six-month backup supply of active carbon filters for your Torus Filtered Water Bowl (sold separately). These filters remove impurities to keep your pet's drinking water clean and fresh. They improve water clarity， reduce odors and remove chloramine， chlorine， phenol， tannins， hydrogen sulfide and other compounds that cause unpleasant odors. Cleaner water is more appealing to your pet and will encourage her to stay hydrated!