Pour 4 cups of undiluted white household vinegar into the water reservoir. Place a paper filter into the filter basket and close. Place empty decanter on the warming plate. Turn the unit on and brew through only 3 cups of the vinegar and stop the unit by unplugging it or turning it off. Let the remaining vinegar stand for 30 minutes. After 30 minutes, pour the vinegar from the decanter back into the coffee maker reservoir and place the empty decanter back on the warming plate. Turn the coffee maker back on to let all the vinegar flow through. When all the vinegar has flowed through, remove the paper filter and brew plain water until the vinegar smell is gone.