How to clean bathroom grout: the method we use every day

How to clean bathroom grout comes down to two things: matching the cleaner to the grout, then giving it time to do the work. The wrong product on Victorian lime grout will eat the joints out of your tiles in a year. The right product on modern epoxy will leave the lines looking like they did the day they were laid. We clean Glasgow bathrooms every day, and the method below is the one we hand new starters on their first week.

This guide walks through the order we follow, the products we actually carry in the van, the dwell times we trust, and how we adjust for the three grout types you tend to find across Glasgow flats: cement-based grout in most modern bathrooms, epoxy grout in higher-end refurbs, and the soft lime-based grout still hiding behind period tiling in older West End and Southside tenements.

How to clean bathroom grout, what is the best product for the job?

For everyday cement grout, the best product is a paste of bicarbonate of soda and a small splash of warm water: apply, leave for fifteen minutes, scrub with a stiff nylon brush, rinse. It is cheap, does not bleach the surrounding tile, and lifts months of soap scum without harming the joint.

For grout that has gone properly grey or black with mould, we step up to a 3% hydrogen peroxide and bicarbonate paste, mixed two parts peroxide to one part bicarb. It bubbles, sits for ten minutes, then scrubs out with a grout brush. Hydrogen peroxide is gentler than bleach, will not strip colour from coloured grout, and is safe on natural stone surrounds.

When peroxide cannot shift it, the paste we reach for next is HG Mould Spray (the proper professional one, not the household supermarket version), left on for the full five minutes the bottle states. We use it on shower corners and silicone joints, never on lime grout in older tenements.

What is the best way to clean bathroom shower grout?

The best way to clean bathroom shower grout is to clean it warm and wet, in two passes, with the extractor fan running. Soap scum and limescale dissolve faster on a warm tile, and a second pass on the bottom third of the cubicle catches the worst build-up where water pools.

Our shower-grout routine, in order:

1. Run the shower hot for two minutes, then turn it off. The steam softens soap film and opens the pores of the grout.
2. Dry-brush loose hair, dust and any flaking mould out of the joints with a stiff dry brush. Doing this wet just turns it into paste.
3. Apply hydrogen peroxide and bicarb paste along every horizontal grout line first, then verticals. Horizontals collect more grime, so they need the longer dwell.
4. Wait ten minutes. Set a timer. If you scrub early it will streak.
5. Scrub each line in one direction with a stiff nylon grout brush. Work from the top of the cubicle down. Do not use a wire brush, it cuts into cement grout.
6. Rinse with the shower head on warm, not hot. Hot water can re-deposit minerals you have just lifted.
7. Buff dry with a microfibre cloth. Wet grout always looks darker, drying it shows you what you actually have.

Total time for a standard 90 by 90 cm cubicle: about 25 minutes including the dwell. The temptation is to rush the wait. Don't, the dwell is where the cleaning actually happens.

What cleans grout without scrubbing?

Nothing fully cleans bathroom grout without any scrubbing, but oxygen-bleach foams come closest. Astonish Mould and Mildew Blaster, or HG Mould Spray, applied generously, left for the maximum dwell on the bottle, then rinsed with a strong shower stream, will lift around 80% of surface mould with no brush at all.

The other route is steam. A handheld steam cleaner with a narrow brush attachment held two centimetres from the grout line for ten seconds per inch will lift soap scum, mould and limescale together, with only a quick microfibre wipe to finish. Steam is what we use on the older Southside flats where the grout is too soft for repeated chemical scrubbing.

Both approaches work, both have a ceiling. Once grout is properly stained black through to the body of the joint, no no-scrub method will pull the colour back. At that point you are looking at re-grouting or a grout pen, and that is a different job.

What should you not clean grout with?

You should not clean grout with neat bleach, vinegar (especially on lime or cement grout), wire brushes, or melamine sponges on coloured grout. Each of these solves the surface problem and creates a worse one underneath.

• Neat household bleach: whitens the surface for a week, then leaves the grout more porous than before, so it stains faster next time. Also strips silicone joints and dulls coloured grout.
• Vinegar or lemon juice: acidic, dissolves the lime in lime-based grout and the calcium binders in cement grout. Fine on sealed epoxy, a slow disaster on anything older.
• Wire brushes or scouring pads: cut visible grooves into cement grout. The line will look cleaner for a fortnight, then the grooves trap more dirt than ever.
• Melamine 'magic' sponges on coloured grout: they are micro-abrasive and will lighten beige or grey grout patchily. Stick to white grout only.
• Steam on cracked or crumbling grout: forces water into the joint and behind the tile. Repair the grout first, then steam.

How do you clean black grout in a Glasgow tenement bathroom?

Black or dark grey grout in a Glasgow tenement is almost always mould rather than dirt, because tenement bathrooms tend to be internal, with poor extraction and high humidity from drying laundry on the pulley. Treat the mould first, then improve the airflow, or you will be back at it in six weeks.

Our tenement-bathroom approach:

1. Identify the grout. If the building is pre-1919 and the bathroom looks original, assume lime-based grout. Test a coin-sized patch with hydrogen peroxide, not bleach. If it foams aggressively or starts to crumble, stop and switch to a soft-bristle brush and warm soapy water only.
2. For modern cement grout (most tenement bathrooms refurbished since the 90s), apply hydrogen peroxide and bicarb paste, full ten minute dwell, scrub firmly. Two passes if needed.
3. For epoxy grout in newer refurbs, you can be more aggressive: HG Mould Spray, five minute dwell, stiff brush, rinse hot. Epoxy will not absorb the peroxide so it works on the surface.
4. Run a cordless dehumidifier in the bathroom for two hours after cleaning. Tenement bathrooms hold damp in the sandstone walls, drying the room properly is half the battle.
5. Replace the silicone if the mould has gone underneath the seal. No cleaner reaches mould inside silicone, you have to cut it out and re-bead.

If your grout has gone fully black and crumbles when you press it with a coin, it is past cleaning. Re-grouting a small bathroom is a half-day job for a tiler, around £150 to £250 in Glasgow, and it resets the whole bathroom.

How often should you clean bathroom grout?

A quick grout wipe weekly, a paste-and-scrub on the shower grout monthly, and a deep grout treatment twice a year is the schedule we use for our regular domestic clients. Households with hard water (most of Glasgow is soft to medium, so this is less of an issue here than further south) can stretch the deep treatment to once a year.

The weekly wipe is the one most people skip and the one that does the most work. After your shower, while the tiles are still warm, run a microfibre cloth along the lower grout lines for sixty seconds. That single minute prevents most of what we are paid to scrub out later.

If your grout has reached the point where weekly maintenance is not going to bring it back, a one-off deep clean is usually the reset. We cover full bathroom grout treatment as part of our one-off deep cleaning service, which is what most of our customers book before listing a flat for sale or after a long tenancy.

Which products do the ScrubClub team actually use?

We carry four products specifically for grout work in the van, and we pick between them based on the grout type and condition we find. Nothing exotic, all available from Screwfix, B&Q or Amazon.

• Bicarbonate of soda (food-grade, large tub): our default for general grime on any grout type.
• Hydrogen peroxide 3% solution: for mould and discolouration on cement and epoxy grout. Cheap from chemists, gentler than bleach.
• HG Mould Spray (professional): for stubborn black mould on modern grout and silicone. Five minute dwell, never on lime grout.
• Astonish Mould and Mildew Blaster: a softer back-up for clients sensitive to stronger sprays.

We do not use steam on every job. It works beautifully on intact modern grout but it is the wrong tool for an older tenement bathroom where the grout is already a bit tired. There, gentle paste and patience wins.

Grout is one piece of a bathroom clean, the order matters too. Our bathroom cleaning checklist for Glasgow tenement flats walks through the full sequence we follow, from extractor fan down to skirtings.

And if the silicone around your shower has gone fuzzy and black despite scrubbing, the answer is usually replacement rather than more cleaner. We talk through when to clean and when to cut it out in our piece on mould around shower silicone.

Should you seal grout after cleaning?

Yes, sealing cement grout once a year is the single best thing you can do to keep it clean: apply a penetrating sealer (we use Lithofin KF Stain Stop) with a small foam brush, two thin coats, twenty four hours after cleaning when the grout is fully dry. Epoxy grout does not need sealing because it is already non-porous, and lime grout in period bathrooms should not be sealed because it needs to breathe.

Sealed grout repels water and soap, so the weekly wipe lasts longer and the next deep treatment is easier. It is a fifteen minute job for a standard bathroom and the sealer is around £15 a bottle for enough product to do four bathrooms.

When is grout past cleaning?

Grout is past cleaning when the joint has cracked, crumbled, or stained right through to the body of the material. At that point no surface treatment will help, and continuing to scrub will only widen the gaps and let water behind the tiles.

The three signs we tell clients to look for: the grout flakes when you run a coin along it, the colour comes off on a damp cloth as a brown tint, or there are visible hairline cracks at the corners where wall tiles meet floor tiles. Any of those and you are looking at re-grouting, not cleaning. A grout pen is a short-term cosmetic fix that lasts about six months.

Most Glasgow tenement bathrooms we see have at least one of those issues somewhere, usually around the bath rim. We will always tell you honestly if cleaning will help or if you need a tiler first. The same Glasgow team has been doing this since 2019, and we would rather lose the booking than charge for a job that will not hold.

If the grout flakes off on your fingernail, no cleaner is bringing it back. Re-grout, then maintain.

If you would rather hand the whole bathroom over for a proper reset, ScrubClub covers regular and deep cleans across the West End, Southside, City Centre and out to Bearsden and Newton Mearns. You can get a quote in 60 seconds on our booking page, no phone call needed.