What is the black/grey/pink/orange slimy stuff in my home?

What is the black/grey/pink/orange slimy stuff in my home?
An Introduction on Serratia Marcescens

If you are experiencing black/grey/pink/orange stains or slippery residues in the shower, in a toilet, at a tap, or in the washing machine, you do not have a water quality problem, and you need not fear a health issue. These residues indicate the presence of naturally-occurring Serratia Marcescens bacteria, which are commonly seen in our area and is commonly found growing in bathrooms (especially on tile grout, shower corners, toilet water lines, and basins), where it manifests as a black, grey, pink, pink-orange, or orange discoloration and leaves a black or grey slimy film feeding off phosphorus-containing materials or fatty substances such as soap and shampoo residue. This residue is harmless to humans.
 

Q: Is this as bad as the toxic black variety? And, if so, how do I get rid of it?

A: Unlike run-of-the-mill green molds like Cladosporium, or the infamous toxic black mold, Stachybotrys chartarum, the pink “mold” in your shower isn’t mold at all. The discoloration comes from a biofilm— also known as a bacterial colony—of Serratia Marcescens. The airborne bacterial species thrives in moist environments like showers, where it feeds on mineral deposits in soap scum and fatty deposits in soap and shampoo residue.
Fortunately, the black, grey, pink, pink-orange, or orange residue (a result of the pigment the bacteria produces) makes it easy to spot and remove from shower, walls, floors, countertops, shower doors, and curtain liners. Using basic household cleaners and the techniques ahead, you can get rid of pink mold on hard and soft shower surfaces and keep it from coming back.
  1. Scrub the biofilm off hard. The stubborn biofilm of Serratia Marcescens  can only be removed through agitation and elbow grease.
  2. Rinse away any loosened biofilm in by either wiping down the scrubbed areas with a wet towel or turning on and detaching the faucets to flush the slime down the drain.
  3. Disinfect these same surfaces. It’s not enough to simply scrub away the color; you need to disinfect the surface to remove any lingering bacteria to prevent its return.
    1. Bleach is your best bet since it does double-duty to kill the last of the bacteria and dissolve stubborn stains left in its wake.
    2. Pour six ounces each of chlorine bleach powder and warm water into a 12-ounce spray bottle, then replace the cap and gently shake the bottle.
    3. Spray the solution directly over the hard surfaces you’ve scrubbed and let the solution dwell in the shower for 10 minutes.
    4. Use a fresh soft-bristle scrub brush to lightly scrub down the sprayed areas, rinse once more, and dry the surfaces with a clean towel or squeegee.
  4. Sanitize shower curtains. Shower curtains are a popular hangout for pink mold since they’re seldom cleaned and usually riddled with soap and shampoo residue. Running your curtain through the washing machine on a gentle wash cycle with warm water effectively removes Serratia Marcescens bacteria and any associated stains.
    1. Be sure to first check the care label of your curtain to ensure that it’s machine-washable, then air-dry the curtain outdoors on a sunny day before re-hanging it in the shower.
 

Keep Biofilm Away.

Serratia Marcescens is one stubborn biofilm that often reappears on hard and soft surfaces exposed to fatty materials or mineral deposits even after you’ve taken these outlined measures to remove it. Make your cleaning responsibilities easier on yourself by heeding these tips for preventing new biofilm from forming:

 

Shower:

 

  • Serratia Marcescens is more likely to spread in damp areas, so towel-dry the hard surfaces of your shower after every use to remove excess water.
  • Use a water-dampened paper towel to wipe away soap or shampoo residue anywhere it collects in the shower after every use. Then, make a second pass over these areas with a dry paper towel.
  • Remove soap scum from hard shower surfaces on a biweekly basis.
    • Spray soap-scum-riddled areas of the shower with a 50-50 solution of white vinegar and warm water combined with one tablespoon of dish soap;
    • Let the solution dwell for 15 minutes;
    • Scrub down the sprayed areas with a soft-bristle brush;
    • Rinse away anything you’ve loosened from the tile and glass, and towel-dry or squeegee all wet surfaces.
  • Machine-wash shower curtains, if you have them, on a monthly basis in a gentle cycle with warm water.
  • Identify and repair leaking shower heads or faucets that may create excessive dampness in the shower.
  • Turn on your bathroom’s exhaust fan before you shower and leave it on for around 20 minutes afterward to help dry out air in the room. The Serratia Marcescens is more likely to spread when there is excess moisture in the air.
  • Keep bathroom windows closed while you shower. Otherwise, being an airborne bacterial species, Serratia Marcescens can waft into your bathroom from outdoors.
 

Toilet Bowl:

 

  • Clean toilet bowl according to directions on the toilet cleaning chemical of your choice.
  • After cleaning and disinfecting, pour ¼ cup of household bleach into the toilet tank. Let sit for 20 minutes and flush several times.
    • Do not let household bleach sit in the bowl or tank for more than 20 minutes as it can damage non-porcelain parts of the toilet.
  • Use care with abrasive cleansers and sponges to avoid scratching the fixtures, which will make them even more susceptible to harboring bacteria.
 

Other Areas:

 

  • Remove and soak your sink aerators in a dilute bleach solution, using an old toothbrush to scrub them.
  • Use a cotton swab soaked in bleach to disinfect the refrigerator water dispenser