How To

What Causes Black Ring In Toilet Bowl

what causes black ring in toilet bowl
Written by Shirin Akter

When you get into a washroom, and the first thing you see is a sparkling white bowl, you feel comfortable using the space. However, in most cases, especially in public toilets, you may find that the bowl has a black thing surrounding it. To me, it looks disgusting, and using that washroom feels so uncomfortable. The black thing is what we call a black ring. The first thing I asked myself when I saw a black circle was, What Causes Black Ring In Toilet Bowl 

We all are passionate about using clean spaces anywhere we go, don’t we? 

Therefore, anything that causes an uncomfortable environment should be eradicated.

How Black Ring Forms on Your Toilet

Whenever you find a black ring on a toilet bowl, you first need to know what causes the black circle in the toilet bowl.

Let’s look at the leading cause of the toilet black ring. Hard water consists of a lot of dissolved impurities. When the water comes into contact with a surface such as showerheads, toilets, and drainage, it deposits these impurities. In the bathrooms, when you flush, water flows into the bowl from the rim jets at the base of the bowl to flush out the waste. 

Over time these impurities build up on the ports and the rim of a toilet bowl. This Hard water deposit provides an ideal environment for microorganisms and other substances to thrive or get stuck such that it doesn’t get flushed away during flashing and makes it extremely difficult to wash even with detergents. One such organism is mold and mildew. 

Mold and Mildew

These microorganisms are fungi and are extremely common in our environment. They come in so many shapes and colors, but the black mold is the most common; therefore gives the hard water deposits their black color. 

One thing these molds all have in common, though, is their ability to thrive in a chronically wet environment. The hard water deposits provide an ideal breeding ground, supplying the microorganism with nutrients. 

This is companied by the fact that the toilet bowl is always wet and allows the microorganism to thrive without fear of being washed into the drainage. The constituents of your waste also play a critical role in this organism’s growth rate.

 If you were curious enough, you would have noticed more mold growth in the toilets of people with diabetes. This is because these people pass a lot of sugar into their waste, which provides an even environment for the moulds to thrive.

These moulds may also be problematic as they release tiny spores that predispose people to allergies and other respiratory conditions that manifest as sneezing.

 Sewage Bacteria

Although they are mildly involved in the blackening, they have massive problems. When moulds are present, this sewage microorganism is often present as they thrive in this environment. 

A sewer microorganism is an organism that usually stays in the sewer surviving on sewer waste. Still, when the environment becomes hot and wet, they climb through the drainage and colonize the black rim of the toilet bowl. 

They are the source of the foul smell when you flush the toilet.

How to Get Rid Of Black Ring on a Toilet Bowl

The appearance of the black ring on a toilet bowl is physically disgusting and is the cause of a sharp pungent smell and, in the worst case, maybe the cause of your constant sneezing. 

So you want to prevent or, at best slow its formation as much as possible, and if it’s already present, you may want to get rid of it. Cleaning this black ring with just an Oxo Good Grips Toilet Brush and detergents is an almost impossible task. Instead, they use bleach, or vinegar is highly efficient.

 The bleach dislodges the hard water deposits, allowing easy scrubbing and killing the entire microorganism that has colonized the area.

Materials you need

  • Bleaching detergent
  • Toilet brush
  • Toilet freshener (especially one with a plastic clip-on)
  • Measuring container (that can hold 100ml)

Here is the best way how to do it:

  • The first thing to do is move away the toilet rug to prevent it from getting wet or getting bleached and the toilet covers to allow you thorough cleaning. 
  • Secondly, due to the strong offensive smell, you may want to open the window and, if possible, have a fan in there. To get clean water, flush the toilet and allow it to fill.
  • Next, measure out about 100mls or a cup full of your favorite bleach cup, after which you pour it into the toilet bowl.
  • Stir the bleach vigorously using a toilet brush. Special care needs to be taken to prevent splashing out of the bleach.
  • Ensure the bleach gets into every part of the bowl, and pay extra attention to the existing black ring and the area under the toilet ring. You can then flash the toilet to clean out the bleach and flesh again to ensure all the bleach is removed.
  • In case you do not have bleaching, the agent doesn’t worry. You can use products likely available in your house: vinegar and baking powder.
  • Sprinkle a generous amount of baking powder on the toilet bowl and ensure it gets to all corners, especially under the ring.
  • Spray the vinegar on the baking powder and expect to hear a fizzing sound from the reaction of the two compounds, similar to the one you get from a can of soda. This fizzing reaction undermines the lodge components so they can be quickly flashed. Flush the toilet to rinse the remnant. And if the stain is still present, repeat the process.

Things to Consider

  • Turn off the valve of the toilet pipe and flush the bathroom multiple times. This ensures the toilet bowl becomes free of water, allowing for scrubbing areas usually below the water.
  • If possible, do not use solid toilet fresheners without clip-on suspenders, as there is a risk of the chemical compounds degrading some toilet components.
  • If you observe water dripping from the side of the toilet bowl, use your local repair agent or the manufacturer’s manual to replace the toilet rubber flapper.


Depending on the manufacturer, chlorine-based bleach is contraindicated. So ensure you consult your supplier or check their manual

If their kids or companion animals are in your house, ensure you use pet-friendly or children-friendly toilet fresheners.

Most toilet fresheners that you can get in your local store may not have chemical compounds that kill off mold and mildew but are last sold just having the ability to remove a stain.

When thoroughly cleaning, remember to remove the toilet freshener and ensure it doesn’t come into contact with the bleaching agent.

Ensure the bleaching agent never come into contact with ammonia, as a dangerous chemical reaction can occur by releasing poisonous fumes.

How to prevent the formation of a black ring on a toilet bowl

Finding out what causes the black ring in the toilet bowl is an important step but knowing how to get rid of the black circle is even more crucial. They say prevention is better than cure. Therefore, preventing the formation of a black ring is essential. 

If you are like me, you want your toilet bowl to be free from black rings every time without the regular vigorous scrubbing; there are some ways of ensuring that your toilet is always sparkling clean. The detergent manufacturers have come up with a product termed toilet fresher.

A very efficient product that every household should put on their shopping list. 

How to Use A Toilet Fresher

First, after a thorough cleaning, you get your toilet fresher and hang it on the rim of the toilet bowl. The toilet freshener varies from one company to the other, and so does the use procedure. But basically, it consists of a stable compound that you can hang on the toilet bowl using stick-on plastic suspenders that you can easily attach to the toilet rim.

When you or any household member use the toilet, the stable compound is washed over with the washout water and is washed over by water trickling down from the toilet Septic tank

The stable compound consists of chemical elements that kill mold and mildew that may try to colonize the toilet bowl, ensuring the toilet bowl becomes stain-free for as long as possible.


We all love seeing a sparkling clean toilet bowl when we get into a washroom, in contrast to that black mold ring on your toilet bowl. Most likely, you have been wondering what causes the black ring in the toilet bowl, haven’t you? 

If you follow the above procedure of eradicating the black ring, I am 100 percent sure it will work. Don’t you want people or friends visiting your house to leave with the right mentality about your cleanliness? Your washroom hygiene should be close to perfect. The rest will follow.

Frequently Asked Questions

Is a black ring on a toilet bowl permanent?

A big no. a black ring in a toilet bowl can remove following the right procedure.

About the author

Shirin Akter

Hi My self Shirin Akhter, I am 24 years and I am a web designer. Also a full-time blogger. I started blogging from a young age and most of my design skills and knowledge are self-taught. I also an expert on SEO, Keyword Research, Website Design, Photoshop expert, Advance Excel, Online researcher, and Affiliate expert.

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