Pink Stains

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 pets 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.

The pinkish film often appears during or after construction or remodeling, when dust and dirt containing Serratia bacteria are stirred up. Once the bacteria is airborne, it will seek a moist location in which it can proliferate. Some people have reported that the pink residue only appears during certain times of the year, when their windows are left open for most of the day. This bacteria is present in a number of environments and wind can carry the airborne bacteria or stir up dust in which the bacteria is present. The appearance of the pink residue can be intensified by the use of activated carbon filters, which remove chlorine from the water. The absence of the normal levels of chlorine in tap water allows Serratia to thrive.

The best solution to this problem is to continually clean the involved surfaces to keep them free from bacteria. Chlorinous compounds work best, but keep in mind that abrasive cleaners may scratch fixtures, making them more susceptible to bacterial growth. Chlorine bleach can be used periodically to disinfect the toilet and help to eliminate the occurence of the pink residue. An easy way to do this is to stir three to five tablespoons of fresh bleach to the toilet tank, flush the toilet to allow the bowl to be disinfected, and add another dose of bleach to the tank as it is refilling. Use of a toilet cake that contains a disinfectant can keep residual disenfectant present in the toilet at all times. By keeping bathtubs and sinks wiped down and dry, the formation of pink residue can be avoided. Cleaning these surfaces with a solution that contains chlorine will also help to minimize the occurence of pink residue.