How to Remove Mildew Stains From Fiberglass Bathtubs

Your bathroom makes an ideal breed ground for mildew due to the high humidity and constant exposure to water.

Caulk and tile grout surrounding your tub are especially suseptible to mildew stains.Caulk and tile grout surrounding your tub are especially suseptible to mildew stains.
Unsightly mildew stains make your bathtub look unclean. Clean mildew stains sooner rather than later. The longer you let it go, the more difficult it will be to remove.

Fill a clean, empty spray bottle with undiluted white vinegar. Spray the vinegar onto the mildew spots.

Let the vinegar sit for a few minutes. Scrub the mildew off of the tub with a rag or scrub brush. Rinse off the vinegar with water.

Mix a solution of 1 part chlorine bleach and 5 parts warm water if the mildew is still there. Use a clean rag to scrub the mildew spots with the bleach solution. Rinse out the bathtub well to get rid of the bleach.

Make a stronger bleach solution for stubborn mildew stains. Mix equal parts bleach and water, then scrub the mildew from the bathtub. Rinse out the tub with clean water.

Things You Will Need

  • Empty spray bottle
  • White vinegar
  • Rags
  • Scrub brush
  • Chlorine bleach
  • Bucket


  • If you have tough-to-reach mildew spots in your tub, such as in corners, soak a cotton ball in the bleach solution. Use the milder ratio of bleach and water first, then move on to the stronger solution if necessary. Sit the cotton ball on the hard to reach spots, leave it there for 20 minutes, then rinse.
  • Spray your tub with vinegar after each use to keep mildew at bay.


  • Never mix bleach and vinegar. After using vinegar for cleaning, make sure to thoroughly rinse the area before using bleach. Mixing bleach and vinegar can produce toxic fumes.
  • Work in a well-ventilated area and wear rubber gloves when using chlorine bleach.

About the Author

Kimbry Parker has been writing since 1998 and has published content on various websites. Parker has experience writing on a variety of topics such as health, parenting, home improvement and decorating. She is a graduate of Purdue University with a Bachelor of Arts in organizational communication.