Coffee contains tannin, giving it a pleasing rich brown color. Unfortunately, that pleasing color stains fabrics and other items easily, leaving dark patches and spots. The best way to remove coffee stains from carpet is to blot them up as soon as a spill happens, followed by a rinse with clean water. That is not always possible, however, especially if you're not aware of the spill when it happens. Even though it's best to clean fresh spills, all is not lost if an old coffee stain is found.
Mix 1/3 cup white vinegar with 2/3 cup water in a spray bottle.
Spray the stain with the vinegar mixture, making sure it is completely wet.
Blot up the vinegar solution using a plain white paper towel.
Mix together 1/4 tsp. dish washing detergent and 1 quart of water. Only use dish washing detergent that does not contain lanolin or bleach.
Wet white paper towels with the detergent solution and blot the stain. Continue blotting, using fresh paper towels as needed, until the stain either fades or disappears.
Fill a spray bottle with clean, fresh water.
Spray the area of the stain with the clean water, blotting with a clean paper towel as you spray. Continue until all of the detergent mixture is rinsed away.
Fold six to eight paper towels into a pad and place over the stain, weighted down with a clean brick, rock or other heavy item that won't be ruined by moisture.
Wait for the spot to dry completely.
Remove the paper towels and check to see whether the stain is still visible. If the stain remains, proceed to Step 12.
Fill a spray bottle with hydrogen peroxide.
Saturate the stain with hydrogen peroxide by spraying the area thoroughly.
Wait one hour and blot the spot with clean paper towels.
Repeat Steps 13 and 14 until the stain is completely gone.
Place a pad of folded paper towels over the spot, weighing down with a brick or rock, until completely dry.