In short

Clean grout with a neutral cleaner, warm water and a nylon brush, and keep acids and hard scrubbing away from it. Cement based grout is porous and alkaline, so vinegar and lemon juice etch it and make it hold dirt sooner. A baking soda paste handles light discoloration, and grout that stays dark after a careful scrub needs a different approach.

Worth remembering

  • Use a neutral cleaner, warm water and a nylon brush. Wire and steel brushes cut into grout.
  • Skip vinegar, lemon juice and descaling products on cement grout and natural stone. Acid etches both.
  • Let the cleaner sit before scrubbing, then rinse well. Cleaner left behind attracts new dirt.
  • Grout that stays dark after a careful scrub is either soiled deep or worn, and needs a different fix.

Why grout is easy to damage

Most grout is cement based. It is porous, slightly rough and alkaline, which is why it soaks up mop water, grease and soap, and why it reacts badly to acid. Wrong products and hard scrubbing wear the surface and open the pores, so the grout takes in dirt faster after every cleaning.

A good deal of what people put down to age is really cleaning damage. Epoxy grout is nonporous and forgives more, but the method below is gentle enough for both kinds. Natural stone tile is the other thing to keep in mind, because many stones are softer than glazed ceramic and react to acid even faster than grout does.

Products and tools to skip

  • Vinegar and lemon juice. They are acids that etch cement grout and can dull or pit natural stone tile such as marble, limestone and travertine.
  • Descalers and rust removers, which are strong acids.
  • Wire brushes, steel wool and metal scrapers, which cut channels into the grout and scratch the glaze.
  • Scouring powders and rough pads, which wear the surface down.
  • Mixed cleaners. Never combine bleach with ammonia or with any acid, because the fumes are dangerous.

A gentle method that works

Open a window, wear rubber gloves and work on one section at a time.

  • Sweep or vacuum first so loose grit does not scratch the tile while you scrub.
  • Try the cleaner on a short stretch of grout or a hidden corner and let it dry before judging the result.
  • Wet the grout lines with warm water, then apply a neutral tile cleaner as its label directs.
  • Leave it to sit for the time on the label, usually several minutes, so the cleaner does the work.
  • Scrub along the lines with a nylon grout brush or a soft toothbrush.
  • Rinse with clean water until no film remains, then dry with a towel.

When a baking soda paste helps

A paste of baking soda and a little water is mildly abrasive and safe on cement grout. Worked in with a soft brush and rinsed away, it lifts light discoloration such as marks in a bathroom or beside a sink. It does little for grout that has turned evenly gray from years of mop water, because that soil sits inside the pores and not on the face of the grout.

When cleaning at home stops working

If the grout looks the same after a careful scrub, the soil has gone below the surface or the grout itself has worn. Crumbling, cracked or missing grout is a repair job, and water can reach whatever lies under the tile, so a tile contractor should look at it.

Dark grout that is simply dirty can be treated by a professional tile cleaner with stronger cleaners and extraction equipment. Ask what the cleaning can and cannot do before you book. Sealing clean, dry grout afterward slows new staining.

Questions, answered

Is vinegar ever safe on grout?

Not on cement grout or natural stone, where acid etches the surface even when diluted and used often. Gentler products clean just as well. When in doubt, use a neutral tile cleaner and warm water, and rinse thoroughly afterward.

Can I use a steam cleaner on grout?

A steam cleaner can loosen soil from sealed grout on glazed tile when held a few seconds from the surface. Keep it off natural stone, loose tiles and cracked or unsealed grout, where hot moisture can get underneath. Wipe up the loosened soil as you go.

How often should grout be cleaned?

Clean floor grout when the lines start to look dull, which for kitchens and entries is often a few times a year. Light, regular cleaning is gentler on grout than an occasional hard scrub, and quick rinsing after mopping helps too.

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