It may be difficult to avoid mold and mildew on your tub mats, shower curtains, and liners. The best way is to toss them in the washing machine in warm water on the gentle cycle. You can add bleach if it is safe to for the material. Tumble dry the curtains and liners on LOW for only 2-3 minutes. Hang the mats and liners to dry. This should prevent mold from growing.