The Petmate Deluxe Fresh Flow is a purifying pet fountain providing free-flowing filtered water throughout the day for your small dog or cat. Perfect for multiple cat households, this award-winning fountain features continuous circulating water and a unique, patented no-splash waterslide. The re-circulating flow and filter provide naturally cool and oxygenated water, attracting pets to drink more in order to help promote their health and well-being. The AC adapter plugs into any standard household outlet. Each unit includes two replaceable charcoal filters. To ensure freshness we recommend that the filter is changed every thirty days.