How to Clean Grout (and When to Call a Pro)

Grout starts out light and slowly turns gray, then dark — especially in kitchens, bathrooms and entryways. That's because grout is porous: mopping pushes dirty water into the lines, where it settles and builds up. Here's how to clean it at home, and when it's time for a deeper clean.

Before you start: know your tile

Ceramic and porcelain tile are tough. Natural stone — marble, travertine, limestone and some slate — is not: acids like vinegar and lemon can etch it permanently. If you're not sure what you have, skip the vinegar and stick to mild, pH-neutral cleaners.

Method 1: Baking soda paste (most tile)

1. Mix baking soda with a little water into a paste.
2. Apply it to the grout lines and let it sit for 10 minutes.
3. Scrub with a stiff nylon brush (a grout brush or old toothbrush).
4. Rinse with clean water and wipe dry.

Method 2: Baking soda and vinegar (ceramic and porcelain only)

After applying the paste, spray with a 1:1 mix of white vinegar and water. Let it fizz for a few minutes, scrub, then rinse thoroughly. Never use vinegar on natural stone.

Method 3: Hydrogen peroxide for light grout

For white or light grout with stains, a paste of baking soda and 3% hydrogen peroxide can brighten it. Test first — peroxide can lighten colored grout.

The one mixture never to make

Never mix bleach with vinegar or ammonia. The combination releases toxic gases. If you use any bleach-based product, use it alone, with good ventilation, and rinse completely before using anything else. And avoid bleach on colored grout — it can leave blotches.

Why DIY only goes so far

Scrubbing cleans the surface of the grout, but soil settles deep in the pores. Professional tile and grout cleaning pre-treats the lines, then uses hot water extraction to rinse away the dirt that mopping and scrubbing leave behind. The difference is often dramatic — see our before and after photos.

Keep it clean longer

• Use a pH-neutral floor cleaner and change the mop water often.
• Dry floors after mopping so dirty water doesn't settle into the grout.
• Consider sealing clean grout — it slows down future staining.

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