Frequently Asked Questions
16. What is this pink residue in my bathroom?

Pink residue is generally not a problem with water quality.  In fact, pink residue is likely a result of airborne bacteria which produce a pinkish or dark gray film on regularly moist surfaces.  Such surfaces include toilet bowls, showerheads, sink drains, and tiles.  Some people have also noted that the pink residue appears in their pet’s water bowl, which causes no apparent harm to the pet and is easily cleaned off.  Due to the expense of having the bacteria tested, most homeowners never identify the exact type of bacteria that is causing their problem.  However, many experts agree that the bacteria that causes these pink stains is most likely Serratia marcesens, a bacteria which is found naturally in soil, food, and in animals.  Serratia, which produce a characteristic red pigment, thrive on moisture, dust, and phosphates and need almost nothing to survive.  These bacteria were thought to be harmless until recently, when it was discovered that in some people, Serratia marcesens is a cause of urinary tract infections, wound infections, and pneumonia.