Use this in place of our expensive, small, inefficient fridge filter. I fitted a reverse osmosis filter bypass plug in place of our fridge filter (supplied with the fridge if your water supply to the fridge is already filtered). Our refrigerator filters are $50 each and the "replace filter" light comes on after 3 months. Instead, I installed this Culligan unit under our sink on the water line that goes to the refrigerator. Problem solved! A much larger filter, cheaper, should last a lot longer.