Woman using a handheld sprayer and sponge to clean bathroom mildew and orange slime in shower

Bathroom Mildew and Orange Slime: Cleaning Mistaken Identities

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Did you know many of us confuse bathroom mildew with a common bacterial growth? I always grew up calling that pink or orange stuff that grows in shower corners mildew, but it’s not. And that’s a good news-bad news thing in cleaning.

The good news is that these are surface issues—they don’t penetrate walls the way mold can. So, you can get rid of them in about a half-hour with my homemade cleaning spray then follow the same prevention steps to keep bathroom mildew and that pink or orange slime from coming back. 

Why that Orange Stuff is Not Mildew

Know how everything these days seems to be decorated in shades of gray? Mildew is a powdery fungus that starts off light and turns darker as it grows. Serratia marcescens is actually a bacterial growth that adds a splash of color, appearing as a pink or orange slime.

Both like soap scum, body oils, and damp places, but you’re more likely to find mildew on vertical, splash-contact surfaces like grout lines, shower doors or curtains, even the walls or ceiling above shower stalls. S. marcescens, will grow on any surface where it can feed on organic matter and the minerals in water that contribute to its color.

For healthy individuals, neither pose a significant risk though mildew can trigger allergy symptoms. But both can be harmful for people with compromised immune systems and for them S. marcescens in particular carries a genuine risk of several serious infections. 

Did You Know?

The vibrant pink or orange color of Serratia marcescens, that unwelcome bathroom film often mistaken for mildew, comes from a pigment called prodigiosin.

Cleaning Steps For Both

Vinegar eliminates powdery black or green mildew and also the slimy pink or orange biofilm of S. marcescens. Where vinegar isn’t appropriate, borax alone can do the job although it may take repeat applications, as I explain.

Step 1: Ventilation and protection.

Whenever you’re cleaning the bathroom, it’s a good idea to open the windows and run the bathroom exhaust fan. This protects you from breathing in cleaning fumes and stirred up germs. Slip on some rubber cleaning gloves, too—the bacteria found in bathrooms aren’t the kind of things you want getting under your skin.

Step 2: Mix up a cleaning solution.

Dissolve half a tablespoon of borax in 1 cup of warm water then add 1 cup of white distilled vinegar. Or, for natural stone surfaces or other materials where vinegar is not appropriate to use, use 1 tablespoon of borax dissolved in 1 quart of warm water instead. 

Step 3: Apply and wait.

Get the area soaking wet—a spray bottle is fine—and give the cleaning solution 15 minutes to break down the growths. Keep an eye on things: you want to ensure it stays wet the entire time so the antifungal and antibacterial properties in borax and vinegar have time to do their job.

Step 4: Scrub and rinse.

With your gloves on, scrub the area with a microfiber cloth. Use plenty of plain water to rinse away the cleaning product and the last traces of the mildew or slime. For very stubborn growths, you may need to repeat the process. 

Did You Know?

The mildew you find in your bathroom is the same type of fungal growth that causes mildew in your laundry.


Now, for some more good news. Once you’ve cleaned the bathroom mildew or orange slime, the same steps can prevent the return of both.

Maintain good ventilation: Run your exhaust fan while showering and for another 15 minutes when you’re done. Open your windows daily to let out moisture, too.

Spread shower curtains: If you have a shower curtain, shake it before getting out of the shower to dislodge excess water. Then leave it open a few inches to either side so air can circulate.

Seal grout: Applying sealant after cleaning grout can protect it from water so mildew won’t grow on it.

Clean regularly: Consistent, regular cleaning does a better job at preventing mildew and bacterial growth than the occasional deep clean. So, follow a weekly bathroom cleaning routine and touch-up surfaces more often as needed.

Keep your shower dry: Use a squeegee or towel to dry your shower walls after use and fix leaky faucets or shower heads promptly.

Or use a daily spray: In busy households, drying the shower after each use may not be practical. Use a no-rinse daily shower spray to eliminate spores and bacteria, and you won’t have to clean bathroom mildew or that orange slime again.

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  1. Patricia W Ferguson says:

    The last one to shower has to spray the shower with vinegar, water, and dawn solution. This helps keep down the need for heavy scrubbing. Now if I could get my husband to clean his sink after shaving, I would have it made.

    1. Katie Berry says:

      IF that happens, be sure to buy a lottery ticket the same day!

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