Torus Bowl Replacement FiltersThe Torus watering bowl uses activated carbon to remove any impurities, to ensure your pet has access to clean, fresh, water every time. Each filter comprises a plastic moulded cone with perforated walls which allow water to flow through. Each Torus filter lasts for approximately a month, so each replacement pack of five filters gives your pet approximately five months of fresh, clean water. The Torus watering bowl comes with one filter to get you