That Pink Residue you see in your sink and tub could actually be bacteria


There are a many folks in Nebraska who take genuine pride in keeping their home “squeaky clean” and sparkling. This can make it especially embarrassing, if not downright frustrating, when one finds a pink residue or stain on bathroom basins, tubs and fittings.  Many homeowners will try to rinse away the pink “gunk” only to find that it reappears soon after. This can lead one to believe, that the pink residue is actually the result of their water quality.  But is it really?That Pink Residue you see in your sink and tub could actually be bacteria

So what is the pink stuff?

Counter intuitively the pink staining is not in fact the result of poor water quality at all. The pink residue is usually an indication of non-harmful bacteria, which tends to develop in moist areas of your home. Typically bathrooms, toilets and showers are likely to be most obvious places, often around sink or tub drains, shower curtains, toilet bowls or shower stalls. However, you may also see signs of pink staining in your kitchen sink or pet water dish.

The most common form of the unsightly pink bacteria in question is Serratia marcescens. There are a number of natural sources for this microorganism, including dust, soil, surface water and mulch. This type of bacteriological organism thrives in moist environments which are high in phosphates.  You may find that you first notice the pink residue during remodeling, after construction dust and dirt is disturbed. Also pink staining tends to be more widespread during the warmer summer months when the humidity and temperatures are higher, especially when the windows have been kept open for extended periods of time.

Like most bacteriological organisms, Serratia cannot survive in chlorinated water, but if the water is left standing for an extended period the residual chlorine will dissipate, which does offer a possible breeding ground for the bacteria. In fact, you may notice the pink staining in less frequently used areas of the home, such as a guest bedroom toilet or shower curtain.  Additionally, if your water supply is filtered using activated carbon, the chlorine levels will be lowered or eliminated altogether and the pink bacteria is more likely to develop.

How to remove pink stains from Serratia marcescens:

Once the Serratia marcescens bacteria have taken hold, it can be difficult to totally eliminate. The most effective way to control an outbreak of pink Serratia marcescens is regular, thorough cleaning with chlorine bleach to disinfect the areas affected:

  • Clean toilet bowls regularly using chlorine bleach or a bleach product.  However, you should not allow bleach to remain in the tank for extended periods of time, as it will cause damage to rubber valves and seals within the tank.
  • Wipe around shower walls and curtains, bathtubs and drains to dry them thoroughly. Once the area is dry, you should spray the area with a product containing bleach.
  • Remember to avoid using abrasive materials or products when cleaning fixtures and surfaces. This can cause minor scratches, which could promote the growth of bacteria in the small crevices and nooks/crannies in the metal.

While chlorine bleach is the most effective way to remove Serratia marcescens’ pink residue, if you have a septic system in your home, you may need to consider the amount of bleach that is allowed to enter your system.

About The Author, Terry Reeh, EcoWater Systems of Nebraska:

With more than 25 years experience in the residential and commercial water treatment space, Terry is a WQA (Water Quality Association) certified water specialist, LEVEL 3, as well as a WQA certified sales representative.  Terry currently sits on EcoWater Systems (a Berkshire Hathaway Company) national Peers committee, as a water treatment expert  advising other water professionals with less experience on best trade and technology practices. EcoWater Systems of Nebraska is one of the biggest water treatment and water delivery businesses in the state.  

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