Cleaning & descaling your Keurig brewer is an important step to enjoying the best tasting coffee and keeping your brewer in good shape for years.
How often you need to do it depends heavily on how often you use your brewer and how "hard" your local water is ("hard" meaning how many minerals are in it). I try to do this 3-4 times a year.
If you notice a vinegar-like smell or taste to the water coming out of your brewer, refill the reservoir with water a second time and run hot water cycles until empty.
Congratulations!! Your Keurig brewer is now clean and your ready to enjoy full cups of delicious coffee for months to come!