Generally, every three to six months a Keurig coffee machine needs cleaning. To clean the parts, unplug the machine and wipe the inside with a clean nonabrasive damp towel. To wash the drip tray, remove it and wash it with warm soapy water. Do the same for the cup holder and water reservoir. Replace the clean parts and then fill the water reservoir with 48 ounces of white vinegar. Brew the vinegar into a cup and repeat three times. Empty out the remainder of the vinegar, fill the reservoir with fresh water, let it stand for about 4 hours and brew until all of the water is gone. Do not place the machine into water.