Considering that water makes up over 95-percent of each cup of coffee (even if you added a copius amount of sugar), microscopic particles and minerals can contaminate the taste of even the best cup of coffee or tea. What a catastrophe if the prime ingredients that fill each Keurig K-Cup meet with distasteful water. Unfortunately, many areas of the USA still have relatively hard water. That's where the Keurig 5072 Water Filter Replacement becomes an essential accessory. It's about health but, most of all, it's taste. Reversible Sleeve - Up to a 10 netbook Manufacturer's 2-year warranty