If you live in an area with hard water, or use well water, your coffee maker will develop mineral deposits, called scale, on the inside of both the pot and the water reservoir. You can purchase chemical descaling solutions from the store or you can use a cheap, household product you already have in your kitchen that will do the job just as well.
Measure one cup of white vinegar and pour it into the water reservoir of your coffee maker.
Fill the remainder of the reservoir with water.
Line the coffee basket with a paper towel or clean coffee filter.
Turn the coffee pot on and allow the vinegar water to brew through the brewing cycle.
Repeat this process a second time if mineral build-up is heavy or not removed with the first cleaning.
Fill the water reservoir with plain water and brew the water though the cycle. This will remove any vinegar taste in the coffee maker.
If you do this on a regular schedule, for instance once a month, mineral deposits will not build up in the coffee maker.