The main attraction of Keurig machines is that they will brew you a cup of top notch coffee in less than 60 seconds. The machine is simple to use and produces the perfect cup of coffee every time as it leaves no margin for human error. The machines are reliable and foolproof, but do require a small amount of cleaning every now and again. Although cleaning the machines may take slightly longer than the 60 seconds it takes to make the coffee, it is not a time consuming process and if done regularly it will keep your coffee maker in optimum condition.
Cleaning the machine should be done once every three to six months, more often if you live in an area with hard water which could lead to build ups of deposits on the inside of your coffee maker.
Method 
Wait until the machine is cold and make sure it is unplugged before starting to clean it. Wipe down the outside of the machine with a damp cloth. Remove the drip tray, cup holder and the funnel. Either wash these parts by hand with warm, soapy water, or they are all safe enough to place in the dishwasher along with the rest of the crockery. The water reservoir can also be washed in the dishwasher although the lid must be washed by hand as it is not dishwasher safe. Replace all of the parts which have been washed into the machine and drain it of any water.
Dealing with hard water issues
If you live in an area with hard water, it is very common to get lime scale deposits caused by the minerals in the water. As the water heats in the maker, the deposits get left behind, and if not cleaned off can affect the machine and stop it working in severe cases. As mineral deposits are alkaline, treating them with an acid can counteract the effects.
The best acid to use for hard water deposits is vinegar. Fill the reservoir of the machine up with while vinegar. Switch the machine on and brew the vinegar, placing a cup to catch it as it comes out. Repeat this process four times in total. Fill the reservoir up with fresh water and allow the machine to sit for at least four hours, preferably overnight. Brew the machine again until the machine is empty, then it is ready to use to make coffee again.
If you don’t live in an area with hard water, there is no need to run the machine through with vinegar and a simple thorough cleaning should be sufficient.
I’ve found that occasionally doing a “descale” doesn’t get the job done and my Keurig starts to not quite finish the brewing cycle. When that happens I just take the machine to the sink and turn it upside down.
That seems to remove any air clogged in the unit and it’s back to it’s old self again.