Black Mold in Shower, Pink or Orange: What It Is and the Fix

Black mold in a shower is usually mold or mildew, a fungus on grout and caulk that never dry out. Pink or orange “mold” usually isn’t mold at all: it’s Serratia marcescens, a bacterium that feeds on soap residue. Both come off sealed tile and grout with a scrub, then a disinfectant used by its label. The exception: growth inside caulk or behind the wall, which scrubbing won’t fix.

Black, pink or orange: what each color usually means

Color gives you a rough idea, not a diagnosis. The CDC notes that mold can show up as spots of many different colors, and that you don’t need to know the type to clean it up.

Color in the shower	What it usually is	How to clean it	When it’s beyond cleaning
Black, gray or dark green spots on grout, caulk or the curtain	Mold or mildew, a fungus	Scrub with detergent and water, dry completely, then disinfect if you want to (label directions)	The stain is under or inside the caulk, it’s on drywall or the ceiling outside the shower, or the patch is bigger than about 10 square feet (EPA)
Pink, salmon or red slimy film around the drain, in grout lines, on the curtain hem	Serratia marcescens, a bacterium	Scrub with a brush and a household cleaner, then a chlorine bleach cleaner, then rinse	Rarely. It comes back if surfaces stay wet, which is a drying problem, not a cleaning one
Orange slimy film	Often the same bacterium: its pigment can be red, pink, magenta or orange	Same as pink	Same as pink
Orange or rust-colored stain that’s hard, not slimy, and follows drips	Possibly iron in the water, which leaves reddish or orange staining (EPA)	Not mold. Use a rust stain remover by its label, and never with bleach	It’s back within days after every cleaning: get the water tested

What is the pink mold in my shower?

Pink “mold” in a shower is usually Serratia marcescens, a bacterium, not a mold. North Dakota State University Extension identifies it as the pink to red substance in toilet bowls, sinks, tiles and shower stalls, growing wherever there’s soap residue or other fatty material to feed on.

It isn’t coming from your pipes, either. NDSU says it isn’t known to be a waterborne disease, and Portland Water District in Maine describes it as a bacterium found in dust and soil that travels through the air and grows wherever it’s damp. Hence the usual spots: the drain ring, the bottom of the curtain liner, the corner where the shampoo bottles sit.

The color comes from a pigment called prodigiosin. A review of Serratia infections in Clinical Microbiology Reviews says it can be red, pink, magenta or orange depending on conditions, so red mold in the shower and orange slime are usually the same thing as the pink.

Is pink mold in the shower dangerous?

For most healthy people, pink film in the shower is low risk, but it isn’t zero. Serratia marcescens is an opportunistic pathogen, meaning it can cause infections under the right circumstances. The Clinical Microbiology Reviews article says most described human cases started in hospitals, and lists long hospital stays, prolonged antibiotics, immune compromise or underlying illness, and devices like catheters as risk factors. It also links Serratia eye infections to contact lenses and lens cases, so keep your lens case and solution out of the shower area.

Michael Taylor, a mycologist at Flinders University, wrote in The Conversation that most people exposed to Serratia won’t get sick or will develop only a mild infection. He also recommends gloves for scrubbing it off.

We’re a cleaning company, so here’s where our part stops. If someone at home has a weakened immune system, wears contacts and has eye trouble, or has any health question about it, talk to a doctor.

What is black mold in the shower?

Black mold in a shower is mold or mildew, a fungus that settles where water sits: grout lines, the caulk along the tub, a curtain hem, the ceiling over a steamy shower. Online, “black mold” usually means one particular species, but you can’t tell the species by looking, and the CDC doesn’t recommend testing. Its advice is to remove mold whatever the type.

Where it grows matters more. On glazed tile and sealed grout it sits on top and scrubs off. In silicone caulk it can be in the material itself. On painted drywall or a ceiling outside the shower it’s on a porous surface, and the EPA says porous materials may have to be thrown out once they’re moldy.

Is black mold in the shower dangerous? The CDC says damp, moldy places may cause a variety of health effects, or none. People with asthma or mold allergies may react severely, and people with weakened immune systems or chronic lung disease may get lung infections from mold. If you have health concerns, the EPA says to talk to a health professional before you start cleaning.

How to clean mold in the shower

Clean first, disinfect second. Spraying disinfectant over soap scum and slime and walking away is the shortcut to skip. The CDC’s bleach guidance says to clean visibly dirty surfaces with soap or detergent before disinfecting, and Taylor’s order is the same: scrub, wipe, then disinfect.

1. Turn on the fan and open a window. The CDC says to make sure you have good ventilation when you use bleach indoors.
2. Put on gloves and eye protection. For mold cleanup the EPA lists gloves, goggles and an N-95 respirator, and says not to touch mold with bare hands.
3. Clear the shower. Bottles, razors, the caddy. Put the curtain liner and bath mat in the wash.
4. Scrub with detergent and water. A stiff brush on the grout lines, the drain ring and the corners. That’s the EPA’s instruction for mold on hard surfaces: scrub with detergent and water, then dry completely.
5. Rinse and look again. Whatever’s still dark after a good scrub is either stained into the grout or growing in the caulk.
6. Disinfect, if you choose to, by the label. For pink film in tubs and showers, NDSU suggests a chlorine bleach solution left on for 10 to 20 minutes, then a good rinse. Mixing your own for mold? The CDC says no more than 1 cup of household bleach per gallon of water. With a store-bought disinfectant, the EPA says the surface has to stay visibly wet for the full contact time on the label, so reapply if it starts drying early.
7. Rinse, then dry everything. Squeegee the walls, towel the ledges and the tub edge, and leave the door or curtain open.

Bleach safety: what never goes together

Never mix bleach with ammonia, vinegar or any other acid. The Washington State Department of Health explains that bleach and ammonia produce toxic gases called chloramines, and bleach plus an acid gives off chlorine gas. Acids hide in more products than you’d think: vinegar, some window cleaners, toilet bowl cleaners, drain openers, rust removers. The CDC’s rule is simpler still: never mix bleach (or any disinfectant) with any other cleaner.

So use one product per session. After a vinegar or rust-stain cleaner, rinse well before bleach goes anywhere near the surface, or leave it for another day. Read the whole label first, and test a hidden spot, since bleach can lighten colored grout, caulk and fabric. And skip the internet “mold killer” recipes that put three products in one bottle.

How to get rid of mold in shower caulk

Scrub caulk the same way as grout. If the dark color is still there afterward, or it’s back within days, the caulk itself is the problem, and the fix is new caulk, not a stronger cleaner.

The sealant makers agree. Loctite’s guide to cleaning silicone caulk says a compromised seal means replacing the entire bead line. GE’s guide describes caulk as porous enough to trap moisture and says to remove old caulk and apply a fresh bead when needed. And the EPA: do not paint or caulk over moldy surfaces. A new bead over the old one just seals the mold in.

You’re past cleaning when you see:

• Black spots under the surface of the bead after scrubbing
• Caulk that’s peeling, cracked or pulling away from the tub or tile
• Mold that comes back in the same spot no matter how often you clean

Cutting out the old caulk, drying the joint and laying a new bead is a handyman job (or a careful weekend DIY). Recaulking isn’t part of our cleaning, and we’d rather say so up front than scrub the same bead every visit.

How to keep mold from coming back in the shower

Shower mold comes back when the shower stays wet, so the fix is getting water and steam out faster. The EPA says bathroom mold can recur, and that better ventilation and more frequent cleaning usually keep it under control. A KUOW report on pink film was blunter: it will almost definitely be back.

• Run the bathroom fan, and leave it on. The EPA says to run bathroom fans or open windows when you shower. The Building America Solution Center, a Department of Energy-funded guide, recommends running the fan for one hour after a shower on a timer switch, so nobody has to remember. It also has to vent outdoors, not into the attic.
• Squeegee and dry after the last shower of the day. NDSU recommends wiping down and drying tubs and sinks after each use.
• Open the curtain or door, and spread the liner flat so the hem dries.
• Get bottles off the ledge. The wet ring under a shampoo bottle is just what pink film needs.
• Switch cleaners now and then. Portland Water District suggests alternating chlorine-based and non-chlorine cleaners for pink film (never mixing them).
• Clean on a schedule, not when it turns pink. Taylor suggests every two to three weeks, depending on how many people use the shower.

That white haze on the glass is a different problem, usually soap scum rather than mold. Our guide on soap scum vs hard water on shower glass covers how to tell and what removes it.

Why Georgia showers have a harder time drying out

NOAA’s long-term averages for the Atlanta airport station put relative humidity at 86 to 87 percent on July and August mornings and around 58 percent in the afternoon. Indoors, the EPA recommends below 60 percent, ideally 30 to 50, and the CDC says no higher than 50. A bathroom that starts the day that humid and then takes a hot shower has a long way to come down, so here the fan and the squeegee matter more than the cleaner. If the whole house runs damp or smells stale, our guide to a musty smell in the house goes room by room.

When to stop cleaning and call someone else

Shower mold on tile, grout and the surface of caulk is a cleaning job. Mold that’s gotten into the building isn’t, whatever a cleaner tells you.

• The area is bigger than about 10 square feet. The EPA says you can usually handle less than that yourself. Above it, look for an experienced mold remediation contractor.
• It’s on drywall, the ceiling or wall paint outside the shower, or that paint is bubbling or peeling. That points to water getting into the wall.
• The wall behind the tile feels soft, tiles are loose, or there’s a stain on the ceiling below the bathroom. Call a plumber or a tile contractor first.
• The caulk keeps failing in the same spot. Get it replaced (see above).
• Someone at home has asthma, a mold allergy, a weakened immune system or lung disease, or symptoms they connect to the shower. Talk to a doctor before anyone scrubs, as the EPA advises.
• Mold shows up on the fan grille or the ceiling around it even though you run the fan. It may not be venting outdoors or moving enough air.

How our deep cleaning handles the shower

Our deep cleaning is the one to book for a shower that’s slipped behind. Its bathroom list cleans the bathtub, sinks and tiles with a steamer, polishes all glass surfaces, shower doors and taps, and disinfects surfaces with antibacterial spray. Those are the surfaces you can see and reach. It doesn’t recaulk, open walls or do mold remediation.

Describe the problem in the booking notes and add a photo of the shower so the team knows what’s waiting. You pick the size by bedrooms and baths, up to six of each, see the total before you confirm, and no payment is taken when you book.

To keep it from sliding back, recurring cleaning repeats the standard list weekly, biweekly or monthly, and every visit cleans the showers, tiles and toilets and finishes with antibacterial spray. Between visits, the fan and the squeegee are on you.

Frequently asked questions

Is pink mold in the shower dangerous?

Pink film in a shower is usually Serratia marcescens, a bacterium. Most people exposed to it don’t get sick or get only a mild infection, and most serious cases described in the medical literature began in hospitals, among people with weakened immune systems or other illness. Wear gloves to clean it, and talk to a doctor with health concerns.

Why does pink mold keep coming back in my shower?

The bacterium behind pink film travels in dust and air and grows wherever soap residue stays wet, so it settles back in after every cleaning. What slows it down is drying: run the exhaust fan after showers, squeegee the walls, open the curtain, keep bottles off the ledge, and clean every two to three weeks.

Can I use bleach on black mold in the shower?

You can, by the product label and after you’ve scrubbed the mold off with detergent and water. The CDC says to use no more than 1 cup of household bleach per gallon of water for mold, with good ventilation. Never mix bleach with ammonia, vinegar or any other cleaner, because the mixtures release toxic gases.

How do you get mold out of shower caulk?

Scrub the caulk with detergent and water and a stiff brush, rinse, and dry it. If dark spots stay under the surface or the caulk is cracked or peeling, the bead needs replacing. Sealant makers say a compromised bead should be replaced, and the EPA says not to caulk over moldy surfaces.

Should I test the mold in my shower?

Usually no. The CDC does not recommend mold testing and says you don’t need to know the type of mold to clean it up. If you can see it, remove it and fix the moisture behind it. A professional assessment makes sense when growth covers more than about 10 square feet or appears inside walls.

How we made this guide

• What our deep cleaning and recurring cleaning include, how booking works and what’s not on the list comes from our service pages for deep cleaning and recurring cleaning.
• Pink film as Serratia marcescens, what it feeds on, cleaning with chlorine bleach for 10 to 20 minutes, and drying after each use: North Dakota State University Extension, Red Substance in Tub, Toilet Is Bacteria. Dust and air as the source and alternating cleaners: Portland Water District, There is pink slime in my shower.
• Prodigiosin, pigment colors, hospital-acquired infections, risk factors and contact lenses: Mahlen, Serratia Infections: from Military Experiments to Current Practice, Clinical Microbiology Reviews, 2011. Infection risk for most people, gloves, scrub before disinfecting and cleaning frequency: Michael Taylor, Flinders University, in The Conversation, republished by 1News. Recurrence: KUOW.
• Scrubbing with detergent and water, the 10 square feet threshold, protective gear, porous materials, not caulking over mold, bathroom ventilation and humidity of 30 to 50 percent: EPA, Mold Cleanup in Your Home and A Brief Guide to Mold, Moisture, and Your Home. Contact time: EPA, Selected EPA-Registered Disinfectants. Iron and orange staining: EPA, Secondary Drinking Water Standards.
• Mold colors, no testing, health effects, 1 cup of bleach per gallon and humidity under 50 percent: CDC, Mold. Cleaning before disinfecting and ventilation with bleach: CDC, Cleaning and Disinfecting with Bleach.
• Bleach with ammonia and acids: Washington State Department of Health, Dangers of Mixing Bleach with Cleaners.
• Replacing caulk: Loctite, How to Clean Silicone Caulk, and GE Sealants, How to Remove Mold from Shower Caulk.
• Running the fan one hour, timer switches and venting outdoors: Building America Solution Center, Bathroom Exhaust Fans.
• Atlanta humidity: NOAA National Centers for Environmental Information, Comparative Climatic Data, relative humidity table (Atlanta, GA station, period of record 1945-2018).