How do you remove mould in the bathroom?

Those black dots in the grout behind the tap. A dark line along the sealant around the shower tray. You sprayed something on it only last month and now it's back. But why does mould in the bathroom keep coming back, and what actually works? In this article you'll find out how to remove mould surface by surface, what to do about the ceiling and what it takes to keep the mould away.

Short answer

Mould in the bathroom forms where moisture sits on a cold surface. On tiles and in grout, you can remove mould with heat and a brush. Mould that has penetrated the sealant can no longer be cleaned and has to be replaced. Removing it is only half the job: without better ventilation, the mould will be back within a few weeks.

Why does mould form in the bathroom?

Mould forms where moisture, warmth and a food source come together, and a bathroom provides all three.

After a shower, the humidity is high. That damp air condenses on the coldest surface in the room, which is usually the outside wall, the window or the ceiling. If that moisture stays there, mould has all it needs within a few days.

The food source is the part people surprisingly often miss. Mould doesn't live on the tile, but on the soap scum, skin cells and shampoo residue left on it. So a bathroom you clean regularly gives mould less to feed on.

Is mould in the bathroom dangerous?

A small patch of mould in the grout is mostly unsightly and easy to tackle yourself.

With larger areas, it's a different story. Mould spores get into the air and can irritate the airways, which is especially noticeable in people with allergies or asthma. So work with a window open and keep the room well ventilated while you're at it.

Does the mould keep coming back in several places, or is the patch larger than about half a square metre? Then it's no longer a cleaning problem but a moisture problem in the structure, and you'll want to have that looked at.

How to remove mould in the bathroom in 5 steps

Below you'll find five steps. You start by ventilating and drying, followed by loosening with heat, wiping away, the follow-up treatment and finally the drying.

1. Open a window first

Ventilate before you start, not afterwards. Open a window or run the mechanical ventilation on its highest setting, so the spores you loosen leave the room. Wear gloves and keep your face out of the steam.

2. Dry the surface

A dry surface lets go, a wet surface smears. Wipe the tiles and grout with a dry cloth first, so you remove the mould later rather than spreading it across the wall.

3. Loosen the mould with heat

Heat kills mould and softens the build-up around it. Hot steam also reaches deep into the porous grout, where a spray only touches the surface. Use the Achaté Handheld Steam Cleaner PRO with the round brush for this: it reaches temperature in three to five minutes and delivers 3.5 bar, enough to get into the grout. Work from top to bottom and in small sections.

4. Wipe it away immediately with a cloth

Whatever you loosen has to leave the room. Wipe the spot with a clean cloth, then throw that cloth away or wash it separately at a high temperature. A cloth you reuse just puts the spores back somewhere else.

5. Let the bathroom dry completely

Drying is the step most people skip, and that's exactly why the mould comes back. Leave the window open for another hour and dry the sealant and the corners with a cloth. Mould starts again as soon as moisture is left standing.

Note: never mix bleach with a cleaner containing ammonia. That combination produces a toxic gas. If you want to work without chemicals, heat is the safest route, especially in a small room with little fresh air.

How do you get mould out of grout?

You remove mould from grout with heat and a narrow brush, because grout is porous and the mould sits inside it.

That's the difference with a tile. A tile has a dense glaze, so the mould sits on top and you simply wipe the spot away. Grout absorbs moisture, which lets the mould take root below the surface.

That's why a spray just sits on the grout and at most bleaches it lighter. What you want is heat and movement right into the grout line.

In practice, it works fastest in two moves. First the steam with the round brush over the grout, then the Achaté Electric Cleaning Brush with the narrow grout head. The steam loosens, the rotating brush lifts it out of the line. If a greyish tint remains after drying, the discolouration is in the grout itself and regrouting is the real solution.

Removing mould from sealant, and when replacing it is better

The same principle works on sealant, but with a clear limit.

If the mould sits on top of the sealant, the build-up comes off with heat and a cloth. Use the pointed nozzle of the Handheld Steam Cleaner PRO instead of the brush, because a brush on soft sealant leaves tiny scratches where dirt actually clings.

Has the sealant itself turned black, and does that colour remain after cleaning? Then the mould has penetrated the sanitary sealant and you won't get it out any more.

In that case, cut out the old seal and apply a new one. It's more work than cleaning, but it's the only thing that lasts. Choose a sanitary sealant with an anti-mould additive and let the seal cure fully before you shower again.

Does a steam cleaner work against mould?

Yes, a steam cleaner works against mould, because heat kills the mould instead of just bleaching the colour.

That's the difference with a bleach-based product. Bleach removes the black colour, so the spot looks clean, while the mould simply carries on living in the pores of the grout. That's why the patch comes back exactly the same two weeks later.

Heat tackles the mould itself. What's more, a steam cleaner runs on tap water. In a small room without a window, that makes a noticeable difference: no fumes, no residue on surfaces you touch with wet hands.

What steam doesn't do is solve the moisture problem. That's still your job.

Mould on the bathroom ceiling: a different problem

On the ceiling, mould isn't caused by soap scum, but by condensation.

Warm, damp air rises and condenses on the coldest surface in the room. That's almost always the ceiling, especially if there's an unheated loft or an outside wall above it. So there's no dirt there feeding the mould, but there is a daily layer of moisture.

That changes the approach in two ways. Don't scrub with lots of water above your head, because it runs back down your arm and the patch ends up bigger than it was. And don't expect cleaning to be enough: on a painted ceiling, the mould often sits in and under the paint layer.

For overhead work, the weight of the device is the difference between ten minutes and giving up. The Handheld Steam Cleaner PRO weighs 1.2 kg, which makes it the model you can hold up to a ceiling long enough. Use short bursts of steam with a cloth over the nozzle, so the moisture is absorbed straight away and doesn't run down.

Is the patch in the paint? Then remove the mould first, let the surface dry completely and then apply an anti-mould paint. Without that last step, the mould will come back in exactly the same spot. If it keeps coming back despite ventilating, there's a cold bridge or a leak, and that's a job for a damp specialist.

Which Achaté product should you use for which spot?

That depends on the surface and on how long you'll be holding the device. In the table below you'll find which model and which attachment does the job for each spot in the bathroom.

Achaté models for each spot in the bathroom

Torn between the two steam models? The rule of thumb is simple. For targeted work on small, tricky spots, grab the handheld steam cleaner, and for large surfaces in one go, the PRO V2.

How do you stop mould from coming back?

How quickly mould comes back depends on how long the bathroom stays damp after showering.

Three things work best, and together they take less than a minute a day:

• Ventilate during and after showering: leave the window open or the ventilation on until the mirror is clear again.
• Squeegee the walls: running a window vac over the tiles and the shower screen removes most of the moisture before it can settle.
• Keep the grout clean: less soap scum means less food, and therefore slower growth.

Do several people shower one after the other? Then the humidity stays high for hours, and an extra fifteen minutes of ventilation matters more than scrubbing.

Want a mould-free bathroom? Choose steam from Achaté

Mould disappears with heat and stays away with dry air. A product that only removes the colour buys you two weeks, after which you're doing the same job again. If you tackle the mould with heat and then ventilate consistently, you break that cycle.

The Achaté Handheld Steam Cleaner PRO is the handy choice for the bathroom and comes with a brush attachment for the grout lines, the sealant and the corners of the shower tray. For a whole bathroom in one go, there's the Achaté Steam Cleaner PRO V2. If the grout is really stubborn, the Achaté Electric Cleaning Brush with the narrow grout head scrubs it afterwards. For residue on the shower screen, a window vac is the quickest tool.

Is the mould not just in the bathroom but also on a wall or a window frame elsewhere in the house? Then the approach differs by surface and there's a separate step-by-step guide ready for you. The same goes for mould in textiles: read how to get mould out of a mattress.

Want to keep your bathroom clean without bleach in a room without a window? Take a look at the Achaté steam cleaners and choose the model that suits your bathroom.

Frequently asked questions about removing mould in the bathroom

What's the best product for mould in the bathroom?

The best product for mould in the bathroom depends on the surface. On tiles and in grout, heat works most thoroughly, because it kills the mould instead of just bleaching the colour. On sealant the mould has penetrated, no product will help and replacing it is the solution. Never mix bleach with a cleaner containing ammonia.

Why does mould in the bathroom keep coming back?

Mould comes back because the moisture problem remains or because only the colour has been removed. Bleach turns the spot white, while the mould lives on in the pores of the grout or sealant. Without better ventilation after showering, the growth starts again within a few weeks.

Can you remove mould with vinegar?

Vinegar works on light build-up on smooth surfaces, but it shouldn't be used on natural stone or on affected sealant. On porous grout, vinegar doesn't penetrate deep enough to reach the mould below the surface. For grout and sealant, heat is a more thorough route.

How long should you ventilate after showering?

Ventilate until the mirror is clear again, because that's when the humidity is back to normal. In a bathroom without a window, that means leaving the mechanical ventilation running for an extra half hour. If several people shower one after the other, you'll need to ventilate for longer.

How do you remove mould from the bathroom ceiling?

Mould on the bathroom ceiling is caused by condensation, so tackle it with as little moisture as possible. Remove the patch, let the surface dry completely and then apply an anti-mould paint if the mould was in the paint layer. If the mould comes back despite ventilating, the cause lies in the structure.