Since K-Cups use a different type of brewing technology there is a separate water tank for the single service. This has some benefits and drawbacks. The good thing is that you can fill it up and use that water immediately, forcing you to use fresh water every time; which is important to get a great tasting cup of coffee.
The downside to that is it isn’t possible to program the K-Cup. Which usually shouldn’t be a problem but the reservoir isn’t kept warm all the time like many other larger, one show pony machines.
While this does save energy, it does take anywhere from 4-6 minutes to brew a cup from the time you push the button to coffee getting in your cup.