How to clean grout and keep it white.
Grout is porous, so it traps dirt and grows mildew faster than the tile around it. The fix is the right cleaner, a stiff brush, and sealing it once it is clean so it stays that way.
Clean grout by spraying it with a baking soda paste or oxygen bleach solution, letting it dwell 10 to 15 minutes, then scrubbing with a stiff grout brush and rinsing. For mildew in a shower, use an oxygen bleach or a diluted bleach solution with ventilation. Once clean and dry, seal the grout to keep dirt out.
Start with baking soda and water
For everyday dingy grout, a paste of baking soda and water is the safest effective option.
- Mix baking soda with enough water to form a paste
- Spread it along the grout lines and let it sit 10-15 minutes
- Scrub with a stiff grout brush or old toothbrush, then rinse
For shower mildew and stains
Bathroom grout grows mildew from constant moisture. Oxygen bleach (a powdered, color-safe option) is gentler than chlorine and works well with dwell time.
- Apply oxygen bleach solution, let dwell 10-15 minutes, scrub, rinse
- For stubborn black mildew, a 1:1 bleach-water spray with good ventilation
- Always ventilate and never mix bleach with other cleaners
Seal it so it stays clean
Clean grout gets dirty again fast because it is porous. After it is fully clean and dry, apply a penetrating grout sealer. Re-seal high-use areas once a year.
- Let grout dry fully (24 hours) before sealing
- Apply penetrating sealer with a brush or applicator
- Wipe excess off the tile before it hazes