Bacteria grows in wet dark places, it is a fact of life. Not all bacteria are bad, and their growth can easily be kept under control. You will need to clean your warmer weekly according to the directions above. To keep bacteria at bay, make sure you check your direction booklet for manufacturer-specific advice. If your warmer comes with a moistening pillow or sponge, make sure to rinse it out weekly and replace it according to your manufacturer’s directed replacement schedule. If your warmer has a water reservoir, you will need to empty it and allow it to completely dry once a week. To keep bacteria at bay, make sure you check your direction booklet for manufacturer-specific advice.