Pink Stains in Bathrooms

Pinks stains in toilet bowl.

There are pink stains that appear in biofilm in bathrooms and other areas of many houses. It will show up on the edges of bathtubs, on shower curtains, near taps, on ceramics, in toilet tanks or bowls, and even in water bowls used for pets. I frequently notice these stains in homes that seemed to have been meticulously cleaned and cared for.

Many people believe it is minerals or other elements in the domestic water supply or some type mildew that are responsible for the pinkish-red stains. It turns out the culprit most of the time is a bacteria known as serratia marcescens.

Serratia marcescens under a microscope.

It is an airborne bacteria that is often present in soil and is introduced into the house through windows and other openings.  It is often found inside homes in new subdivisions. Likely the digging and turning up soil during construction is teasing the bacteria out into the air. The bacteria appears to be pathogenic to some people therefore regular cleaning of the biofilm is advised.

Here’s a website that briefly explains the concept and how to keep the bacteria at bay. Along with regular cleaning it is also important thing is to keep standing water on surfaces to a minimum. Shower squeegees are used for this purpose.