When “Water Filter Status Light” inside the fridge door goes red, replace with Whirlpool #4396841 ornMaytag # W10193691 available at Lowes, Home Depot, or Reliable Parts (3727 So. ‘G’ St. by LincolnnHigh). The box will tell you what models and numbers of filters it will replace. Per directions, run 3ngallons of water through system with replacement filter before it is usable. Watch out, at first it willnburp air and splash water! Push reset button per directions to get green light. Tip for less cost buy 2 onnline at: Reliable Parts or Amazon.com; where If you set up a scheduled purchase (Subscribe and Save)nthey take 5% off. The two-pack saves more than the single.nhttp://www.amazon.com/Whirlpool-4396841-Button-Refrigerator-filter/dp/B000UW2DTE/ref=pd_bxgy_hi_text_yt