Pink Mould in the Shower: Why It Happens and How to Get Rid of It

That faintly pink-orange film along the silicone seal, the bottom of the shower curtain, the corners of the shower tray, the underside of the soap dish — that's pink mould. Or technically, it's not even mould. The biology is more interesting and the fix is more reliable than the "scrub harder with bleach" approach almost everyone tries first.

Pink mould is one of the most-googled UK bathroom problems for a reason: it keeps coming back. Bleach kills it temporarily and it's back within two weeks. White vinegar gets rid of it longer. But the only permanent fix is changing the conditions that let it grow in the first place.

Here's the proper guide.

It's not actually mould

The pink-to-orange film in your shower is Serratia marcescens, a bacterium — not a fungus. This matters because it changes what kills it and how. Mould-specific cleaners aren't optimised for bacterial colonies, which is part of why "anti-mould" sprays keep failing on the pink stuff.

Serratia is everywhere in the air outdoors, comes in on water droplets, and feeds on the soap scum, body oils, and shampoo residue that coat shower surfaces. Given moisture, warmth (above 18°C), and a food source, it forms biofilm colonies within 48–72 hours. The pink colour is a pigment the bacterium produces called prodigiosin — useless to the bacterium itself but a handy visual signal for us that it's there.

It's mostly harmless to healthy adults but worth taking seriously: it can cause skin irritation, eye infections, and (rarely) urinary tract infections, especially in immunocompromised households, young children, and elderly people. Worth getting rid of properly.

Where it grows in UK bathrooms

Pink mould doesn't appear randomly. It colonises specific surfaces in this order:

1. Silicone seals — especially the bead between the tiles and the bath/shower tray
2. Grout lines, particularly at low points where water pools
3. Shower curtain hems and bottom edges
4. Shower tray corners where water sits between uses
5. The underside of soap dishes, bath toys, and shampoo bottle bases
6. Shower head spray plates
7. Inside drain covers

If you have pink mould in one of these and not the others, the source is the location where water sits longest. Fix that location and the rest stops happening too.

How to get rid of pink mould (the actual method)

Step 1 — Pre-rinse and dry the area

Rinse the affected surface with hot water from the shower for 30 seconds to soften the biofilm and remove loose debris. Towel-dry. The cleaner needs to make direct contact with the bacteria, not get diluted by surface water.

Step 2 — Spray with white vinegar, neat

Put neat distilled white vinegar (the regular supermarket 5% kind) in a spray bottle. Saturate the affected surface generously. Don't dilute — the acetic acid is what kills the biofilm. Leave for 15 minutes minimum, 30 ideally.

Vinegar works better than bleach here for two reasons: it kills the bacteria and breaks down the biofilm that protects them. Bleach kills the surface layer but the biofilm shields deeper layers, which is why pink mould comes back so fast after bleach.

For stubborn old colonies: after the vinegar contact time, sprinkle bicarbonate of soda directly over the wet surface. It'll fizz where it meets the vinegar — the agitation helps the acid penetrate into grout pores and silicone microcracks.

Step 3 — Scrub gently with a soft brush

A soft-bristled brush (an old toothbrush works fine for small areas) gently scrubbed along the silicone or grout lifts the broken-down biofilm. Don't use a stiff metal brush — you'll damage the silicone, which creates more microcracks for the next colony to live in.

For shower curtains: take them down and machine-wash on a 40°C cycle with a normal dose of detergent plus a cup of white vinegar in the fabric softener compartment. Air-dry — don't tumble.

For shower heads: soak in a plastic bag of neat vinegar tied around the head with an elastic band, 4 hours minimum.

Step 4 — Rinse and dry thoroughly

Rinse with clean water. Dry completely with a microfibre cloth or paper towel. The crucial step: leave the bathroom dry for at least 4 hours afterwards (run the extractor fan, open the window, no showers). Damp = re-colonisation.

Step 5 — Stop the conditions that caused it

This is the bit most online guides skip. Without changing the conditions, pink mould comes back within 2 weeks no matter how thoroughly you killed it. The prevention section below is genuinely more important than the cleaning method.

What about bleach?

Bleach works on the visible surface. It doesn't penetrate biofilm. So 48 hours after a bleach clean, the deeper biofilm reactivates and the pink is back. That's why pink mould has the reputation of "always coming back" — the bleach approach is the standard advice and the standard advice doesn't work long-term.

Bleach also damages silicone over time (yellows it, makes it brittle, creates more cracks for bacteria), corrodes chrome fittings, and is a respiratory irritant. The white vinegar method works better and doesn't have those downsides.

If you want the rapid surface clean of bleach + the lasting effect of vinegar: use vinegar as described above, rinse, then apply a small amount of bleach gel (Cillit Bang Power Cleaner or similar) just to the silicone bead and leave for 30 minutes before rinsing. This is the heavy-duty approach for grout that's been pink-mould-stained for years and has visible pigment.

Why pink mould keeps coming back — and how to stop it

Five conditions feed Serratia. Eliminate any of them and the bacteria can't establish.

Condition 1 — Standing water

Anywhere water pools for more than an hour is a colony in waiting. Wipe down:

• Shower tray after every shower (a small squeegee £3 from Wilko)
• Tiles and silicone around the bath after baths
• The shower screen after showers

30 seconds with a squeegee or microfibre cloth after every shower is by far the single most effective prevention measure. UK households who do this never see pink mould.

Condition 2 — Humidity above 60%

UK bathrooms run high humidity for hours after a shower if ventilation is poor. Two fixes:

• Run the extractor fan during the shower AND for 20 minutes after. Most UK fans run only during the shower or briefly after — not enough.
• Open the window for 10 minutes after the shower. If the bathroom doesn't have a window, a small dehumidifier (£30–£50 from Argos) makes a measurable difference.

Condition 3 — Soap residue

Serratia feeds on the soap scum that coats every shower surface. Reduce the food supply:

• Switch from bar soap to liquid body wash (less residue stays on the wall)
• Switch from synthetic-fragrance shower products to plant-based (synthetic fragrance accelerates biofilm growth)
• Rinse walls and tiles briefly with hot water after your shower — takes 10 seconds

Condition 4 — Temperature above 18°C

UK bathrooms in winter are sometimes too cold for rapid Serratia growth, but central heating + closed bathroom door keeps them at 20°C+ year-round. You can't realistically change this, but knowing it explains why pink mould is worse in centrally-heated UK homes than draughty old cottages.

Condition 5 — Damaged silicone

Old, cracked, or yellowed silicone has microcracks that hold bacteria in places no cleaner can reach. Once silicone is more than 5 years old or visibly damaged, the only permanent fix is to replace it. £5 for a tube of bathroom sealant, an hour's work, and the silicone is fresh for another 5 years.

Re-siliconing instructions:

1. Cut the old silicone out with a sharp blade or silicone remover tool
2. Clean the gap with white vinegar, leave 30 min, dry completely
3. Apply silicone remover gel (Unibond) to any residue, scrape off
4. Apply new bathroom silicone with a caulking gun
5. Smooth with a wet finger
6. Leave 24 hours before water contact

This is the long-term fix for shower silicone that's been pink for years.

Pink mould on specific surfaces

Shower curtain

Machine wash at 40°C with white vinegar in the rinse cycle (200ml). Air dry — don't tumble. If the colour is set in (some plastic curtains absorb the pigment), replace it — £5–£15 from any UK supermarket.

Silicone seals

Vinegar method above. For old yellowed silicone that doesn't respond to vinegar, replace the silicone (instructions above).

Grout

Vinegar + bicarbonate of soda paste, scrub gently with a brush. For deep-set staining, use a bleach-based grout cleaner (HG Mould Remover, Astonish Mould Remover) on the grout specifically, not the tile. 30 minutes, rinse, neutralise with white vinegar afterwards.

Shower head

Tie a plastic sandwich bag of neat white vinegar around the head with an elastic band, leave 4 hours, scrub the spray plate with an old toothbrush, run the shower for 30 seconds to clear.

Bath toys

Soak in hot water + white vinegar for 30 minutes, scrub corners with a brush. Squeeze rubber ducks etc. to flush water out completely before storing. Replace toys that have visible pink colonies on the inside — if you can see pink mould through a hole in a bath toy, the inside is unreachable and the toy needs binning.

Drain covers

Remove if possible, soak in hot water + vinegar for 30 minutes, scrub thoroughly. Pour a kettle of boiling water down the drain after cleaning to sterilise the pipework below.

What doesn't work

• Antibacterial sprays aimed at kitchens. Most aren't optimised for bathroom biofilm; surface-only effect.
• Tea tree oil alone. Has mild antibacterial properties but not strong enough to kill an established colony.
• "Scrubbing more vigorously" without a chemical agent. Damages silicone, doesn't kill the biofilm.
• Wiping with a damp cloth. Just redistributes the bacteria. Dry contact is the goal.
• Closing the bathroom door after a shower to "let the moisture clear naturally". The opposite — traps humidity and feeds the bacteria.

Should you call in a professional?

Almost never necessary for pink mould specifically. If the colony has spread to ceiling corners, into wall cavities visible at the edge of tiles, or you're seeing pink-then-black mould together, that's a different problem — likely a leak or damp issue, and worth a plumber or damp specialist. Otherwise, the DIY method above is reliable.

Frequently asked questions

What is pink mould in the shower?

It's not actually mould — it's a bacterium called Serratia marcescens. It produces a pink-orange pigment (prodigiosin) and forms biofilm colonies on damp surfaces with soap residue. Common in UK bathrooms because of high humidity and warmth from central heating.

Is pink mould dangerous?

Mostly harmless to healthy adults but worth taking seriously. Can cause skin irritation, eye infections, and (rarely) urinary tract infections, especially in immunocompromised households, young children, and elderly people. Treat it promptly, especially if anyone has reduced immunity.

What kills pink mould permanently?

Neat white vinegar applied for 15–30 minutes kills the bacteria and breaks down the protective biofilm. Bleach only kills the surface layer, which is why pink mould comes back fast after a bleach clean. Pair the vinegar method with prevention (squeegee after every shower, run extractor fan for 20 minutes after) to stop it returning.

Why does my shower keep getting pink mould?

Five conditions feed Serratia: standing water, humidity above 60%, soap residue, temperature above 18°C, and damaged silicone. UK bathrooms tick four of these by default. The most impactful single change is squeegeeing the shower after every use (30 seconds) and running the extractor fan for 20 minutes afterwards.

Does bleach kill pink mould?

Only on the surface. Bleach doesn't penetrate the biofilm that protects deeper layers of bacteria, which is why pink mould returns within 2 weeks of a bleach clean. White vinegar breaks down the biofilm itself, which is why it lasts longer.

How do I prevent pink mould in the shower?

Squeegee the shower walls and tray after every use, run the extractor fan during the shower and for 20 minutes after, switch to plant-based shower products (less synthetic fragrance feeding the biofilm), and replace silicone if it's older than 5 years. Doing all four eliminates the conditions Serratia needs.

Why is pink mould worse in winter in the UK?

Central heating keeps the bathroom at 20°C+ all winter, ventilation suffers because nobody opens windows in January, and water lingers longer on surfaces. Net effect: warm humid stagnant conditions that Serratia thrives in. The fix is more ventilation and routine drying-after-use.

Can I get rid of pink mould without bleach?

Yes — white vinegar is more effective long-term than bleach. Apply neat for 15–30 minutes, scrub gently with a soft brush, rinse, dry thoroughly. For stubborn grout staining, add a bicarbonate of soda paste on top of the vinegar for extra abrasion.

Why does pink mould grow on my shower curtain?

Plastic shower curtains stay damp longer than tiles after each shower, and the bottom hem traps water and soap residue. Take the curtain down regularly and machine wash at 40°C with white vinegar in the rinse cycle. Replace if pink staining has set into the plastic.

Should I re-silicone my shower to stop pink mould?

Yes, if the silicone is more than 5 years old or visibly damaged. Old silicone has microcracks that hold bacteria in places no cleaner can reach. Re-siliconing is £5 of sealant and an hour's work, and resets the surface for another 5 years.

Got a bathroom-cleaning question we haven't covered? Email us — family of three, no support script.