Machine Washable Bath Mats
Fill your washing machine with water and adjust the cycle to use the hottest water possible. High temperatures kill mold spores.
Add ½ cup of distilled white vinegar. White vinegar will help remove the mold.
Put the moldy bath mat in the vinegar water and shut the lid to start the cycle.
Remove the bath mat from the washing machine.
Put the bath mat in a dryer and adjust the heat to the highest that the bath mat can handle. If the bath mat manufacturer does not recommend machine drying the bath mat, hang it over a hanger until it is completely dry.
Non-Machine Washable Bath Mats
Remove as much of the mold growth as possible by scrubbing the mold area with a dry toothbrush. This will flake off a lot of the mold, but will probably not remove all of it.
Mix 1 cup water with 1 cup rubbing alcohol.
Dab the rubbing alcohol solution onto the moldy area until you remove as much of the mold as possible.
Mix 1 cup white vinegar with 1 cup water if mold is still present on the rug. Dab the vinegar solution over the moldy areas until you remove all of it.
Rinse the bath mat with clear water to remove the vinegar and the rubbing alcohol solutions. Hang the bath mat to dry completely.