How to Clean Bathroom Grout
Written by Shannon, Owner and Founder of Long Island MaidsDingy, discolored grout makes even clean tile look dirty. Grout is porous, so it absorbs moisture, soap, and grime over time. Here's how to restore it to like-new condition—and keep it that way.
Why Grout Gets So Dirty
Grout is made of cement, which is porous. It absorbs everything: water, soap residue, body oils, mold spores, and dirt. Unlike glazed tile that wipes clean, grout traps contaminants in its microscopic pores. That's why grout darkens over time, even with regular cleaning.
What You'll Need
The Best DIY Grout Cleaner
This baking soda + hydrogen peroxide paste is the most effective homemade grout cleaner.
Make the Paste
Mix ½ cup baking soda with ¼ cup hydrogen peroxide (3%) to form a thick paste. Add a few drops of dish soap for extra cleaning power.
Apply to Grout Lines
Use your finger or an old toothbrush to apply the paste directly to grout lines. Cover all discolored areas generously.
Let It Work
Wait 10-15 minutes. For heavily stained grout, wait 30 minutes or longer. The peroxide and baking soda work together to lift stains and kill mold.
Scrub
Scrub with a stiff grout brush or old toothbrush using circular motions. Apply pressure but don't damage the grout. Work in small sections.
Rinse and Dry
Rinse thoroughly with warm water. Wipe with a clean cloth or mop. Dry completely to prevent new mold growth.
Alternative Cleaning Methods
Spray undiluted white vinegar on grout, wait 10 minutes, scrub and rinse. Good for regular maintenance but may not tackle heavy stains.
Mix 1 part bleach with 10 parts water. Apply to grout, wait 10 minutes, scrub and rinse. Effective for mold but use with ventilation. Don't use on colored grout.
Dissolve oxygen bleach in warm water per package directions. Apply to grout, let sit 15-30 minutes, scrub and rinse. Safer than chlorine bleach and effective.
Steam cleaners blast hot steam into grout pores, loosening dirt and killing mold without chemicals. Follow with a wipe-down. Great for regular deep cleaning.
For Stubborn Stains
Black Mold in Grout
- Apply undiluted bleach or mold remover to the affected grout
- Let sit 15-30 minutes
- Scrub with a stiff brush
- Rinse and dry thoroughly
- For persistent mold, repeat or use a mold-killing primer before resealing
Rust Stains
Use a commercial rust remover containing oxalic acid (like Bar Keepers Friend). Apply, wait 10 minutes, scrub gently, and rinse. Don't use bleach on rust—it sets the stain.
Deep-Set Discoloration
If grout is stained beyond cleaning, consider grout colorant or grout pen. These products coat the grout with a new color, essentially repainting it. Apply after thorough cleaning.
Sealing Your Grout
After deep cleaning, seal your grout to prevent future staining. Unsealed grout will get dirty again quickly.
- Wait 24-48 hours after cleaning for grout to dry completely
- Apply grout sealer with a small brush or applicator bottle
- Let sealer penetrate 5-10 minutes
- Wipe away excess from tile surfaces
- Allow to cure per product directions (usually 24 hours)
- Reapply annually for best protection
Keeping Grout Clean
- Weekly spray: Spray grout with vinegar solution weekly to prevent buildup
- Squeegee after showers: Removes water before minerals can deposit
- Ventilate: Run exhaust fan to reduce moisture and prevent mold
- Spot clean spills: Wipe up shampoo, soap, or other products immediately
- Reseal annually: Grout sealer wears off—reapply yearly
- Monthly scrub: Quick monthly maintenance prevents heavy buildup
When to Re-Grout
If grout is cracked, crumbling, or has deep mold that won't clean out, it may need replacement:
- Grout crumbling or falling out
- Visible gaps between tiles
- Mold that returns immediately after cleaning
- Water getting behind tiles (causes loose tiles)
Re-grouting is a DIY-able project but requires removing old grout first. For extensive work, consider a tile professional.
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Frequently Asked Questions
Why does grout get dirty so quickly?
Grout is made of cement, which is porous. It absorbs water, soap residue, body oils, mold spores, and dirt. Unlike glazed tile that wipes clean, grout traps contaminants in its microscopic pores. This is why sealing grout after cleaning is so important for prevention.
What's the best homemade grout cleaner?
The most effective DIY grout cleaner is a paste of baking soda and hydrogen peroxide (3%). Mix ½ cup baking soda with ¼ cup peroxide, add a few drops of dish soap. Apply to grout, wait 10-30 minutes, scrub and rinse. The peroxide whitens while baking soda provides gentle abrasion.
Can I use bleach on grout?
Yes, diluted bleach (1 part bleach to 10 parts water) is effective for mold and mildew in grout. However, don't use bleach on colored grout as it may discolor it. Never mix bleach with vinegar or ammonia as this creates toxic gases. Use with good ventilation.
How often should I seal my grout?
Seal grout annually for best protection. Grout sealer creates a barrier that prevents moisture and stains from penetrating the porous surface. Apply after deep cleaning, wait 24-48 hours for grout to dry completely, then apply sealer and let cure per product directions.
When should I re-grout instead of cleaning?
Consider re-grouting if grout is crumbling or falling out, you see visible gaps between tiles, mold returns immediately after cleaning (indicating it's deep in the grout), or water is getting behind tiles causing them to loosen. Re-grouting is a DIY project but requires removing old grout first.
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