The new Drinkwell Original 12 (4 - 3 Packs) Pet Filters should be changes every 4-8 weeks depending on the size and number of pets using the fountain. 12 filters should be a 2 year supply The filters packaging comes with detailed directions and diagrams on how to remove and install the filters in your Drinkwell Pet Fountain. The Drinkwell Original Pet Filters are Name Brand and new in full retail packaging (Not Private Label)