The pink slimy residue that’s most often found in the bathroom and around sinks/drains is not mold or an issue of water quality. The discoloration comes from evidence of a common bacterial inhabitant of our environment. This airborne bacteria, scientifically known as Serratia marcescens, produce a characteristic red pigment and is found naturally in soil, food, and animals and needs almost nothing to survive.
Serratia marcescens can be more prevalent when temperatures and humidity are high. It is most often found on regularly moist surfaces, including toilet bowls, showerheads, shower curtains, shower walls and floors, sinks, drains, and tiles. The bacteria feed on mineral deposits in soap scum and fatty deposits in soap and shampoo residue. Although Serratia marcescens will not survive in chlorinated drinking water, it will develop in the water where the residual chlorine has dissipated, such as a pet’s water bowl.
Serratia marcescens isn’t difficult to kill but if appropriate preventative measures aren’t taken, a new colony will likely grow. The best solution is to continually clean and disinfect the surfaces to keep them free of bacteria. Once clean, follow these guidelines to prevent it from returning: