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What Causes Pink Stains on Toilets and Bathtubs?

May 15, 2024

What Causes Pink Stains on Toilets and Bathtubs?

Are you noticing pink stains in your bathtub, shower, or toilet? These stains are a common complaint that most homeowners assume is a question of water quality but it comes from another source entirely in most cases. We'll explain what causes this problem, how it causes it, and what you can do about it.

What Causes Pink Stains?

If you're seeing pink stains in your bathroom, the problem is not usually water quality. Pink stains in bathtubs, toilets, and showers are caused by a bacteria called Serratia marcescens, which is found naturally in the environment. This bacteria is airborne and finds a home on moist surfaces. The bacteria growth leaves pink slime at the water line in the toilet bowl, on shower doors, around sink and tub drains, and on the walls of bathtubs. These airborne bacteria thrive on moisture, dust, and phosphates, which are found in bathroom environments.

How Does Serratia Marcescens Cause Pink Stains?

When this bacteria spreads and multiplies, it produces a natural red-orange pigment named prodigiosin. With water to dilute it, this red color leads to pinkish stains - it's been known to look like blood when undiluted, which would certainly be an interesting and slightly terrifying stain to see in your bathtub or toilet!

How To Eliminate the Stains & the Bacteria

A bleach-based toilet bowl cleaner is the best way to eliminate the bacteria. Occasionally, flushing toilets that are not used often can also help reduce bacteria growth. You can also try mixing vinegar and water sprayed over the affected area. The bacteria thrive on dampness, so keeping humidity under control in affected areas can also help. Use your bathroom fan during and after showers, or crack a window for ventilation.