How to Get Rid of Bathroom Mould for Good

Slug: how-to-get-rid-of-bathroom-mouldPillar: Practical Living > CleaningKeyword: how to get rid of bathroom mouldExcerpt: Bathroom mould is more than unsightly — it can harm your health. Here's how to remove it safely and stop it from coming back, step by step.

Why Bathroom Mould Keeps Coming Back

Mould thrives in warm, damp, poorly ventilated spaces — which makes bathrooms its favourite home. The most common culprits are black mould (Stachybotrys chartarum) and the milder pink-tinged Serratia marcescens bacteria. If you've scrubbed it away only to find it returns within weeks, you're treating the symptom, not the cause.

The key to permanent removal is a two-part approach: kill the existing colony, then fix the conditions that allowed it to grow.

What You'll Need

Before you start, gather: white vinegar or a diluted bleach solution (1 part bleach to 10 parts water), a spray bottle, an old toothbrush or grout brush, rubber gloves, safety goggles, a face mask rated FFP2 or higher, and a microfibre cloth. Avoid mixing bleach with any other cleaner — even vinegar — as this creates toxic fumes.

Step-by-Step Mould Removal

Step 1: Ventilate the Room

Open windows and switch on the extractor fan. If you have neither, place a fan pointing outward in the doorway to draw air through. Good ventilation protects you from both chemical fumes and mould spores.

Step 2: Apply Your Cleaning Solution

For surface mould on tiles and grout, spray undiluted white vinegar generously and leave it for at least 30 minutes. Vinegar kills around 82% of mould species and is safe to use on most surfaces. For heavier infestations on non-porous surfaces like ceramic tiles, a diluted bleach spray (1:10 ratio) is more effective — but never use it on coloured grout without testing a small area first.

Step 3: Scrub Thoroughly

Use an old toothbrush or grout brush to work into grout lines and silicone seals. These narrow spaces harbour the root structure of the mould colony (called hyphae), so surface scrubbing alone won't be enough. Rinse with warm water and dry the area completely.

Step 4: Tackle Silicone Sealant

Silicone sealant around bath edges and shower trays is notoriously difficult to clean because mould penetrates the material rather than sitting on the surface. If the sealant is heavily discoloured, replace it. Use a silicone remover tool, strip out the old seal, clean the gap with bleach, allow it to dry for 24 hours, and apply fresh mould-resistant sealant. This takes around an hour and can be done without specialist tools.

Step 5: Treat Painted Walls and Ceilings

Bathroom ceilings are a common mould hotspot. After cleaning with a diluted bleach solution, let the surface dry fully, then apply a specialist anti-mould paint. Brands like Polycell and Dulux both make bathroom-rated versions that contain fungicide. One coat significantly slows regrowth.

Stopping Mould From Returning

Cleaning is only half the battle. These habits will prevent regrowth:

Run the extractor fan during and for 20 minutes after every shower or bath. If you don't have one, even cracking a window makes a measurable difference. Squeegee shower walls after each use — this removes around 75% of the moisture that feeds mould. Dry towels outside the bathroom when possible; a damp towel on a hook contributes significantly to ambient humidity. Use a dehumidifier if your bathroom has no window — modern compact models cost under £50 and can reduce relative humidity from 80% to below 60%, making mould growth difficult.

If mould reappears despite these measures, it may indicate a structural issue — inadequate ventilation, a leaking pipe, or condensation from a cold wall. In this case, contact a damp specialist or your local council's housing department for an assessment.

When to Call a Professional

If the mould covers an area larger than one square metre, penetrates behind tiles, or is accompanied by a persistent musty smell even after cleaning, you likely have a deeper moisture problem. The NHS advises seeking professional remediation for large mould infestations, particularly for households with young children, elderly residents, or anyone with respiratory conditions such as asthma.

For rented properties in the UK, landlords are legally required under the Homes (Fitness for Human Habitation) Act 2018 to address mould caused by structural problems. Report it in writing and keep a record.

Quick-Reference Prevention Checklist

Run the extractor fan for 20 minutes post-shower; squeegee shower walls daily; replace silicone sealant every 3–5 years; use anti-mould paint on walls and ceilings; ventilate the bathroom even in winter; and fix dripping taps and leaks promptly.

Frequently Asked Questions

Is bathroom mould dangerous?

Most common bathroom moulds are irritants rather than acutely toxic, but prolonged exposure can worsen asthma and allergies, and trigger respiratory symptoms. Black mould (Stachybotrys) is more concerning and should be treated promptly. The NHS recommends tackling mould quickly regardless of type.

Does white vinegar really kill mould?

Yes — undiluted white vinegar kills around 82% of mould species and is effective for most bathroom surfaces. It's less powerful than bleach on porous materials, but safer for everyday use and suitable for coloured grout.

Can I paint over mould?

No. Painting over mould without treating it first is a common mistake — the mould continues to grow beneath the paint and will eventually bleed through. Always kill and remove the mould, let the surface dry fully, then paint.

How long does it take for mould to grow back?

In a humid, poorly ventilated bathroom, mould can regrow within 24–48 hours if moisture is not controlled. With good ventilation and regular cleaning, you can keep it at bay for months or years.

Does bleach kill mould permanently?

Bleach kills surface mould on non-porous materials but does not penetrate porous surfaces like grout. That's why mould returns in grout lines even after bleaching. A combination of bleach treatment and physical scrubbing, followed by resealing, is more effective long-term.

For more home cleaning and maintenance tips, visit our Practical Living hub, or explore our Home Improvement guides for bigger projects.