We've been using this product for a couple of years now.   It really works great most of the time.   The reason I didn't give it 5 stars is that just a few weeks ago, the new filter we installed got clogged up somehow and the water wouldn't drain through it.   Needless to say a clogged filter is not useful.   We love the tester that comes with the product and the spout at the bottom.   It fits perfectly in our refrigerator.