How to Get Rid of Mold in Bathtub Caulk

Heat and moisture are the main cause of mold and mildew growing in bathtub or shower caulking. Bathrooms with insufficient ventilation provide a perfect atmosphere for mold and mildew -- two names for the same substance -- to grow. Left unchecked, mold will continue to spread behind tile and drywall, and ultimately become airborne. Black mold, in particular, can cause serious health issues. According to the Centers for Disease Control and Prevention, continuous exposure to black mold has been linked to upper respiratory diseases.

corner mold
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Bathroom black mold and mildew

Things You Need

  • Rubber gloves
  • N-95 respirator
  • Long sleeve shirt
  • Safety glasses
  • Box knife
  • Blades
  • Scraper
  • Caulk removal tool
  • Old toothbrush
  • Bleach
  • Dish soap
  • Bucket
  • Spray bottle
  • Rags
  • 6-mil plastic
  • Small 6-mil trash bag
  • Dropcloths


Cover any nearby carpeted areas with plastic and a dropcloth to prevent discoloration. Put on your rubber gloves, safety glasses and respirator. Fill the bucket with 1 gallon of hot water. Add 2 cups of bleach and 1/2 cup of dish soap. If possible, open a window for ventilation. Turn on the exhaust fan, if you have one, to help draw the bleach fumes outside. Fill the spray bottle with the bleach solution. Saturate the affected caulking, and allow it to soak for at least 30 minutes.

Cleaning the Caulk

Saturate the caulking a second time. Use your old toothbrush to scrub the mold and mildew off the caulking. Dip the rag into the bucket of bleach solution; wring it out, and wipe the scrubbed area. Continue this process until all of the affected caulking is thoroughly cleaned. Place your toothbrush, plastic, rubber gloves and rags into the 6-mil trash bag and dispose of it at a hazardous waste facility. Wash the dropcloths in hot water before reusing.

Caulking Removal

If the mold has penetrated the caulking, you'll need to remove and replace it. Over time, mold and mildew begin to grow not only on the caulking, but in it and behind it. When this happens, there is no other alternative but to remove it. Use all the same safety precautions you would to clean mold off the caulk. Cut along the top and bottom edges of the caulking with a box knife blade. Use your scraper to pry behind the loosened caulking. Once you get a strip pried out, use the scraper to push behind the line of caulking to remove it. Place the caulking in a 6-mil trash bag. Use the bleach solution to clean all affected areas before applying new caulking. Dispose of the rags, toothbrush and caulking at a hazardous waste facility.


Periodically clean all caulked areas with a mold and mildew remover.

Install an exhaust fan if you don't have one. The lack of air movement along with heat and moisture causes mold growth.

Use caulking that's designed for kitchens and baths.


Do not use bleach for a prolonged period of time without a respirator. The fumes are toxic.

Do not attempt mold cleaning and removal without the proper protective gear. Black mold causes illness.