I've been using these filters for several years now and I'm very satisfied of how well they filter out contaminants.  The only thing that keeps me from giving this product five stars is that sometimes when I'm filling up my water pitcher, the water just sits there.  I have to pour a stream of water into the filter itself to displace any bubbles or small air pockets that keep the water from flowing into the filter.  Once that's done, the water flows into the filter as usual.