Pink Mold in Your Shower: It's Bacteria, Not Mold

Pink mold in a shower is usually not mold at all. It is a slimy film of bacteria, most often Serratia marcescens, which shows up in shower corners and basins as a pink, orange or red stain because it makes a pigment called prodigiosin^[1]. It feeds on soap residue and grows wherever surfaces stay wet^[2].

For most healthy people it is a cleaning problem, not a medical one. It matters more for people with weak immune defenses, contact lens wearers and anyone with a catheter or line. Below: what the pink film is, why it keeps coming back, who should be careful, and the cleaning steps that public agencies actually recommend.

What is pink mold, and what does it look like?

Pink mold (or pink mould) is a bacterial biofilm. It looks like a slimy pink, orange or red film in shower corners, along caulk and around basins and drains^[1]. In most bathrooms the main organism is Serratia marcescens, a rod-shaped, Gram-negative bacterium that is common in soil, water, dust and feces^[2][3]. You can read more about the organism itself on our Serratia marcescens guide.

The color comes from prodigiosin. Not every strain makes it, and pigment production drops sharply at body temperature. In a 2019 lab study, transcription of the pigment genes fell at 37 °C compared with 30 °C^[4]. That is one reason the film looks so vivid on a cool tiled corner.

Bathroom films are rarely a single species. A study of four household vinyl shower curtains found that the "soap scum" was a dense, highly complex biofilm dominated by Sphingomonas and Methylobacterium bacteria^[5]. Methylobacterium belongs to a group known as pink pigmented facultative methylotrophs^[6]. Pink or red yeasts in the genus Rhodotorula can tint wet surfaces too^[7].

You cannot tell these apart by eye, and for cleaning you do not need to. The same steps remove all of them.

What causes pink mold in the shower?

Water plus residue. The bacteria grow in any moist spot where fatty or phosphorus-containing material builds up, such as soap residue in tubs, feces in toilet bowls and food residue in pet dishes^[2]. A shower stall gives it all three: warmth, water and a steady supply of soap and skin oils.

The answer to "can a person cause pink mold in the shower?" is yes, in the sense that bathing feeds it. Researchers who sampled one home's shower stall and kitchen sink found a rich microbial community, with bacteria outnumbering fungi by about 25 to 1, and volatile compounds that mostly came from microbes breaking down fats^[9]. The bacteria arrive from the environment. Your routine supplies the food.

Common triggers include:

• Poor ventilation, so surfaces never dry between showers^[10].
• Soap and shampoo film left in corners, on caulk and around drains^[2].
• Chlorine-removing filters. A water utility fact sheet notes that removing chlorine with an activated carbon filter can make the pink bacteria worse^[2].
• Scratched fixtures, which give the film more places to anchor^[2].

Pink mold is not a sign that your tap water is unsafe. The same utility says the bacterium is not known to cause waterborne disease^[2]. A 2024 review lists it among less common opportunistic pathogens found in drinking water systems and says its public health risk from drinking water is still unclear^[11].

Is pink mold dangerous, and can it make you sick?

For healthy people, usually not. For some people, it can be. Serratia marcescens was once thought harmless, but by the mid-1960s it was recognized as a definite human pathogen^[12]. It causes urinary tract infections, wound infections and hospital outbreaks^[1], and its infections occur mainly in people whose immune defenses are weakened^[3].

Most serious infections happen in hospitals, not homes. Outbreaks are strikingly often traced to point sources such as medical devices and solutions given to patients^[12]. In one neonatal unit, 44% of sink drain samples tested positive over three years, while no faucet sample did^[13]. Many hospital strains resist several antibiotics, which makes those infections harder to treat^[12].

Who should be careful

• Contact lens wearers. S. marcescens is one of the three most common bacteria in contact lens keratitis, alongside Pseudomonas aeruginosa and Staphylococcus, in a review of 2,916 episodes^[14]. It is often linked to contaminated lens solutions^[15].
• Premature and very low birth weight babies. In a 2025 meta-analysis of 12 studies, prematurity nearly tripled the odds of Serratia infection or colonization in neonates (OR 2.90), and reported death rates in neonatal units ranged from 22.4% to 58.0%^[16].
• People with catheters, central lines or breathing tubes. The bacterium forms biofilms that colonize devices^[3], and invasive devices raised infection risk in neonates^[16]. In hospital settings it has also caused pneumonia^[2].
• Anyone who is immunocompromised, since infections occur mainly in people with weakened immune defenses^[3]. Rhodotorula infections follow the same pattern: 87% of 128 reported cases involved immunosuppression or cancer^[8].

If someone in your home falls into one of these groups, clean pink film promptly and ask their care team whether they need extra precautions.

Is pink mold as bad as black mold?

They are different problems. Pink film is a surface biofilm you can scrub off. "Black mold" usually refers to Stachybotrys chartarum, a fungus; some molds can produce potentially toxic substances called mycotoxins^[10]. See our black mold guide for that organism.

Black or green spots near the pink film, a musty smell or water damage are signs to look past the surface. Our guide to the warning signs of mold exposure covers symptoms.

How to get rid of pink mold in the shower

Scrub first, then disinfect, then dry. Gwinnett County's water utility recommends this sequence for bathrooms, kitchens and pet dishes^[2]:

1. Ventilate and protect yourself. Open a window or run the fan. With bleach, wear gloves made of natural rubber, nitrile, neoprene or PVC, and goggles without vent holes^[10].
2. Scrub the film off with a brush and a household cleanser or detergent^[2][10]. Mechanical scrubbing matters because biofilms tolerate disinfectant chemicals better than free-floating bacteria^[17].
3. Disinfect with a chlorine bleach solution and leave it on for 10 to 20 minutes^[2]. Follow the product label for dilution.
4. Rinse thoroughly with clean water^[2].
5. Dry the surface completely^[10].

Avoid harsh abrasives on fixtures. Scratches make surfaces easier for the bacteria to colonize^[2].

Never mix bleach with other cleaners. Household bleach can release chlorine gas when mixed with certain other products^[18], and the EPA warns specifically against mixing it with anything containing ammonia^[10]. If you smell strong fumes, open windows, leave the room and call Poison Help at 1-800-222-1222^[18].

Does vinegar kill pink mold?

Not reliably at cleaning strength. In standardized lab tests, acetic acid at the concentrations commonly used for cleaning did not have a disinfecting effect; it took 10% acetic acid with 1.5% citric acid to reach a disinfecting level^[19]. A separate lab study found acetic acid inhibited Serratia isolates in a test tube^[20], but that test did not involve a mature biofilm on tile. Vinegar helps loosen soap scum, but it is not a substitute for scrubbing and drying, and it must never be combined with bleach^[18].

Bleach-free options

If you prefer to avoid bleach, the EPA's general advice for hard surfaces is to scrub with detergent and water and dry completely^[10]. Expect to repeat this more often, because once the organism is established it usually cannot be eliminated entirely^[2].

Why are there pink stains in my toilet bowl?

A pink ring in the toilet is the same bacteria feeding on waste residue at the waterline^[2]. It tends to return quickly because the bowl is always wet.

To control it, the Gwinnett County utility advises^[2]:

• Clean the bowl thoroughly, then spray chlorine bleach into the bowl and under the rim.
• Add 1/4 cup of bleach to the tank and let it stand for 15 to 20 minutes.
• Do not leave bleach in the tank for long periods, because it damages the rubber valves and seals.
• Repeat whenever the pink film reappears.

How to keep pink mold from coming back

Pink mold returns because the conditions that grew it are still there. On dry surfaces, S. marcescens can survive for months^[21], so the goal is control, not sterility^[2].

• Run the bathroom exhaust fan or open a window during and after showers^[10].
• Keep indoor humidity below 60%, ideally 30% to 50%. A humidity meter costs about $10 to $50^[10].
• Wipe tubs and sinks dry after use^[2].
• Clean more often in spots where growth keeps reappearing, which the EPA says will usually prevent recurrence or keep it to a minimum^[10].
• Wash or replace shower curtains and liners regularly^[5].
• Clean pet dishes and humidifier tanks on a schedule, since the bacteria grow in any moist spot with residue^[2].
• Fix leaks quickly. Dry wet areas within 24 to 48 hours^[10].
• Protect your eyes. If you wear contact lenses, follow strict lens and case hygiene; a review notes that hygiene is the most important defense against Serratia on lenses^[15].

When to call a professional

Pink film on tile, grout and fixtures is a do-it-yourself job. The EPA says you can usually handle moldy areas under about 10 square feet yourself^[10]. Consider a professional when:

• growth covers more than about 10 square feet, or there has been significant water damage^[10];
• you smell mold but cannot see the source, which can point to hidden growth behind walls or tile^[10];
• black or green growth appears alongside the pink film;
• someone in the home has health concerns, in which case the EPA advises consulting a health professional before cleanup^[10].

Our guide to mold testing at home explains when an inspection adds value and when it does not.

This article is for general educational purposes and is not medical advice. Pink films in the home are usually harmless to healthy people but can matter for vulnerable household members. Talk to a qualified healthcare professional if you have symptoms or concerns, particularly if you are pregnant, immunocompromised, wear contact lenses, use a catheter or other medical device, or care for a premature infant.