What Causes Toilet Bowl Rings?

Toilet bowl rings are unsightly and, if left unattended, may develop into health hazards for humans or pets. While some of the toilet bowl is perpetually wet, other areas are made wet occasionally and then allowed to dry before becoming wet again. This constant state of wetness encourages the growth of bacteria, molds and mildew, which form into toilet bowl rings. Minerals in the water supply and even the chemicals used to clean toilet bowls may also lead to toilet bowl rings.

Toilet bowl rings are stains caused by bacteria, molds, minerals or chemicals.

Accumulation of Serratia Marcescens

The pink to blotchy red ring that often accumulates just above the water line in a toilet bowl is caused by bacteria. Serratia marcescens thrives in conditions that are wet and see a constant introduction of fat or phosphorous-laden materials, such as feces, soap products and/or food products. Serratia marcescens has been found to be responsible for many infections, including urinary tract infections. Mt. View-Edgewood Water Company maintains that Serratia marcescens cannot be completely killed and removed, but routine maintenance can keep the bacteria from increasing. Use chlorine bleach to scrub the toilet bowl ring and beneath the rim around the bowl. Pour 1/4 cup of chlorine bleach into the tank of the toilet and allow it to disinfect for about 20 minutes. Flush the toilet multiple times to remove the bleach.

Mold or Mildew Build-up

Mold or mildew manifests in your toilet bowl as a black, orangey or green ring that also can spread in streaks up or down the inside of the bowl. Black mold often leaves dark stains. Many toilet bowl cleaners are available in spray-on or leave-in formats that effectively clean mold and mildew rings from the toilet bowl with weekly to monthly cleanings. These cleaners dissolve the mold ring and are rinsed away the next time the toilet is flushed. Chlorine bleach can also remove the black stain left behind by a ring of mold.

Mineral Deposits

Toilet bowl rings may be caused by hard water with an acidic, low pH level. White crusty deposits may accumulate around the bowl from water rich in calcium or magnesium. These deposits, often seen as white to gray-hued bowl rings, may be reduced or eliminated entirely with the installation of a water softener system or by treating your water with a water softener.

Toilet bowl rings that look like rust stains are caused by an abundance of iron in the water. These rings are sometimes the most difficult to remove as cleaners that include bleach actually make the stain permanent. "The Family Handyman Magazine" suggests cleaning the ring with a diluted form of hydrochloric acid found at home improvement or hardware stores instead.

Discoloration from Cleaning Chemicals

Many cleaning chemicals intended to disinfect and clean a toilet bowl actually lead to a permanent toilet bowl ring stain above the waterline or around the bowl. According to the Environmental Health Association of Nova Scotia, most toilet bowl cleaners contain dangerous chemicals which produce equally dangerous gases. Some of these chemicals, when used constantly over time, will strip the glossy finish from the toilet bowl, creating a dull ring that is a slightly different color than the bowl. The EHANS recommends using natural cleaning methods instead, such as soaking two denture cleanser tablets in the bowl overnight, or allowing 1/4 cup white vinegar mixed with 1 cup borax to soak in the bowl's water overnight.