Petmate Fresh Flow Filter Replacement 3 Pack Fits Jumbo and Medium Fresh Flow The filter reduces bacteria in your pet drinking water. The three pack will give you three months of water filtration. Petmate recommends replacing filters every 30 days (more often if you have more than 1 pet). The charcoal filter removes odors to give your pet fresher drinking water. Charcoal filter removes contaminants from your pets drinking water.