How to Clean Grout and When to Regrout Instead

Grout is the detail that makes or breaks tiled surfaces. Clean, fresh grout makes tiles look cared for, while dark or crumbling grout makes a whole room look neglected. The first decision is whether to clean it or replace it. Knowing how to clean grout, and when cleaning will not be enough, saves both money and wasted effort.

Can Your Grout Be Cleaned, or Does It Need Replacing?

Surface discolouration from general use, soap scum, and hard water is almost always cleanable. If grout that was once light has simply darkened over time and still feels solid, a proper deep clean will usually restore it.

Regrouting is needed when the grout is physically failing: crumbling, powdering, cracking, sounding hollow when tapped, or pulling away from the tile edges. Deep black staining that does not shift with cleaning is usually mould that has penetrated below the surface, which also calls for replacement.

How to Deep Clean Grout

Mix an oxygen-bleach powder cleaner with hot water and apply it generously to the grout lines. Let it sit for 20 to 30 minutes so it can break down staining rather than just lifting surface dirt. Scrub firmly with a stiff grout brush or an old toothbrush, working along the lines in both directions, then rinse thoroughly. For stubborn areas, apply a second time and cover with plastic film for a few hours before scrubbing again.

How to Regrout a Tiled Surface

If the grout is failing, regrouting involves three steps. First, remove the old grout to a depth of at least two millimetres using a grout saw or an oscillating tool, then vacuum out all the dust. Second, apply new grout with a rubber float, working it firmly into the joints at a diagonal angle in small sections. Third, once it begins to firm up, wipe the surface with a damp sponge to remove the haze, then let it cure fully before exposing it to water.

Seal the Grout Afterward

Once grout is clean or newly applied and cured, apply a grout sealer. This creates a barrier that resists staining and makes future cleaning easier. Reapply annually in high-use wet areas like showers.

How to Keep Grout Clean Longer

Wipe down tiled surfaces regularly, ventilate wet rooms to reduce mould, and reseal grout annually. A little routine maintenance prevents the deep staining that makes grout look old in the first place.

Frequently Asked Questions

What is the best homemade grout cleaner?

A paste of baking soda and water scrubbed in, followed by a spray of white vinegar, works for light staining. For tougher jobs, an oxygen-bleach powder dissolved in hot water is more effective and safe for most grout.

Why does grout turn black?

Black grout is usually mould, which thrives in damp, poorly ventilated areas like showers. Surface mould can be cleaned, but mould that has grown deep into the grout often means the grout needs replacing.

Is it better to clean or replace grout?

Clean it if it is simply stained but still solid. Replace it if it is crumbling, cracking, hollow-sounding, pulling away from tiles, or stained with mould that will not clean off.

How often should grout be sealed?

Reseal grout in high-use wet areas about once a year. In drier areas it can last longer. Sealing makes grout much easier to keep clean and far more resistant to staining.

For more on avoiding costly tiling problems, read our guide on what to look for in a building inspection report.