A K-Cup is only designed to brew 1 cup of coffee. The design of the K-Cup allows it to only be used one time and then discarded.
A K-Cup is a plastic cup that holds ground coffee and is equipped with a coffee filter. It is sealed tight for freshness until use. When the K-Cup is positioned inside the brewing chamber, the machine punches a small hole in the top of the K-Cup and then forces hot water into the K-Cup. Coffee is brewed quickly, usually in under a minute, and dispensed into a waiting cup. Once the coffee is dispensed, the K-Cup is removed and thrown away.