How to Remove Mildew Stains in Grout

Mildew is a common problem in humid areas.

Mildew often plagues grout, that hardened material between tiles, because of its porous properties and installation in humid rooms, such as bathrooms. Depending on the severity of the mildew on the grout, you may have to repeat the steps a few times to completely remove the mildew and mildew stains. Before you attempt to remove mildew grout stains, be sure the mildew is thoroughly cleansed from the grout.

Things You'll Need

• Rubber gloves
• Two buckets
• Measuring cup
• Liquid chlorine bleach
• Liquid laundry detergent
• Trisodium phosphate (TSP)
• Water
• Old toothbrush
• Clean rags
• Oxygen bleach product, such as OxiClean

Instructions

Remove Mildew

1. Put on rubber gloves.

2. Pour 2 cups liquid chlorine bleach, 1 tablespoon liquid laundry detergent, 3 tablespoons trisodium phosphate (TSP) and 3 quarts of water into a bucket.

3. Fill another bucket with plain, warm water.

4. Dip the toothbrush into the bucket with the cleaning solution. Scrub a section of the grout.

5. Frequently dip a clean rag into the bucket of plain water, and wipe the cleaning solution from the tiles.

Remove Mildew Stains

1. Fill a bucket with plain, warm water.

2. Put 1 cup of warm water into the other bucket. Mix in approximately 1/2 cup of oxygen bleach powder to the water to create a paste. Add more powder or more water as necessary to create a paste the consistency of watery mud.

3. Dip the toothbrush into the paste and apply it to the grout. Scrub gently.

4. Dip a clean rag into the bucket with plain, warm water. Rinse the paste from the grout and tiles.

5. Repeat Steps 3 and 4 as needed.

Tips & Warnings

• Mildew stains on grout are very difficult to remove. It's best to prevent mildew growth by allowing for adequate ventilation and frequent, preventative cleaning.

• Oxygen bleach is environmentally friendly, and the waste can be disposed into the septic or sewer system.

• Never mix cleaning chemicals before reading the labels on the cleaning containers. Some mixtures, such as ammonia with chlorine bleach or dish detergent with chlorine bleach, are toxic and can cause serious respiratory problems.

• Trisodium phosphate, also known as TSP, is a caustic chemical that can cause skin burns; use with extreme caution. Do not use trisodium phosphate on metals such as chrome, brass or plumbing fixtures, as TSP will stain them. Do not leave TSP on ceramic tile surfaces, as TSP will etch and damage the tile glazing.

References

• University of Florida: How to Prevent and Remove Mildew
• Mrs. Clean: How To Clean Grout and Remove Stains