According to Martha Stewart, all coffee makers should be cleaned once a month. The only items needed for the cleaning project are equal amounts of distilled white vinegar and water. Fill the water reservoir of the coffee maker with the vinegar mixture, let it sit and then turn it on. Allow several cups of the liquid to run through the appliance for a thorough cleaning.
Turn the coffee maker off, and let the liquid remain in the water reservoir for at least an hour. Turn the appliance back on again, and let it complete the brewing cycle. Discard the vinegar mixture, and then run fresh water through the coffee maker for several cycles until all of the vinegar odor disappears. Clean the coffee carafe and the filter basket by running them through the dishwasher in the top rack after scrubbing the mesh filter with a toothbrush, if necessary, to remove coffee-ground buildup. Wipe the outside of the appliance with a damp dishcloth. Commercial products are also available to clean and de-scale a coffee maker.
According to Martha Stewart, coffee makers need to be cleaned each month because an oily residue results from repeated coffee brewing. That residue combines with deposits from hard water and other impurities to build up inside the coffee maker over time. This residue greatly affects the smooth flavor of a cup of coffee.