What Causes the Pink Stuff in Toilets and Showers-and How to Keep It Away

Why Does That Pink Buildup Keep Coming Back in My Toilet and Shower?

If you've ever noticed a pinkish or orange-colored ring forming around your toilet bowl, shower drain, or pet's water dish, you're not alone. This common bathroom annoyance may look like rust or mold, but it’s actually something entirely different—and unfortunately, no water filter or water softener can completely eliminate it.

What Is That Pink Stuff?

That unsightly pink buildup is most commonly caused by an airborne bacterium called Serratia marcescens. This bacteria thrives in warm, moist environments and feeds on soap scum, shampoo residue, and other organic materials commonly found in bathrooms and kitchens.

While it’s not considered highly dangerous, Serratia marcescens can trigger infections in people with weakened immune systems and is a known irritant. For most households, however, the concern is aesthetic—this slimy, stubborn stain is just plain gross.

It’s Not in Your Water—It’s in the Air

Here’s the key thing to understand: This isn’t a problem with your water quality. The bacteria isn’t coming through your pipes. It’s airborne, meaning it floats around in the air and lands on wet surfaces—like the inside of your toilet bowl or your shower wall—where it starts to grow and multiply.

Because of this, no water treatment system can eliminate it. Even the most advanced reverse osmosis systems or whole-home filters can’t remove a problem that doesn’t start in your plumbing in the first place.

Why Is It So Hard to Get Rid Of?

Serratia marcescens is resilient. You might scrub it away only to see it come back days later. This is because as long as your home has moisture and airborne bacteria (which all homes do), the conditions are right for this pink buildup to reappear.

Bathrooms, especially those with poor ventilation, are ideal environments for this bacteria. Toilet bowls that are rarely flushed or cleaned, or sinks and showers that stay damp, are particularly vulnerable.

How to Control the Buildup

While you can’t completely eliminate Serratia marcescens, there are steps you can take to keep it under control:

• Keep surfaces dry: Wipe down your shower or tub after use.

• Clean frequently: Regularly disinfect toilets, sinks, and tubs with a bathroom cleaner or bleach solution.

• Improve ventilation: Use exhaust fans to reduce humidity in bathrooms.

• Flush toilets regularly: Especially in guest bathrooms or those that are rarely used.

Should You Be Worried?

For most homeowners, Serratia marcescens is more of a nuisance than a threat. It’s not a sign of dirty water, nor does it mean your water treatment system isn’t working. Even homes with top-tier water filtration systems will deal with this issue from time to time.

If you’re still unsure whether your water system is working properly or if you’re dealing with other staining or contamination issues, Clean Water Ohio offers free water testing to rule out water-borne contaminants and recommend the right treatment solutions for your home.

Serving Columbus, Dublin, Hilliard, Delaware County, and Central Ohio, Clean Water Ohio is your local expert in water filtration and purification—but when it comes to airborne bacteria like Serratia marcescens, know that it’s not your water—it’s your environment.

Schedule a free consultation today to ensure the rest of your water is clean, soft, and safe for your family.