Amazing, seriously..my newer Keurig (6 months old) was already exhibiting signs of hard water residue, white mineral roughness on the inside of water holding tank. And I only use bottled water for filling. I used the descaling liquid as instructions said and ran through the recommended amounts. I than did a full rinse per instructions and wow! My water holding tank is looking brand new. Without any scrubbing, it all came off and the plastic is smooth as when I took our of the box. I soaked and rinsed the enclosed charcoal filter and added it in tank to help filter water also. My coffee tastes better and the pods also flow quicker. I will definitely continue to buy this in order to keep my Keurig looking new and running great. Easy to understand instructions. Keep your keurig looking and performing like new!!