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How To Get Rid of Black Streaks in Toilet

No one likes to see an unclean toilet. Especially not one that is full of black streaks that look like they have been fermenting in there for ages. 

If your toilet bears these black marks, I’m afraid you have been negligent with cleaning it regularly. If you take the time to regularly clean your toilet bowl, it won’t have the time to develop any staining, black, yellow or green. 

However, let’s not lament the past and let’s see what you can do to get rid of the black streaks in your toilet today. 

How To Get Rid of Black Streaks in the Toilet

Black streaks in your toilet can be caused by mould, bacteria or mineral deposits. You can use baking soda and vinegar, borax and vinegar, a toilet cleaner or bleach to get rid of them. 

The most likely cause of persistent black streaks are mineral deposits from hard water. They can be removed by a DIY solution, like baking soda and vinegar, but you can always buy a commercial toilet cleaner too. It’s more likely to be more efficient on particularly persistent staining. 

You could also have missed some mould below the rim, which has now spread and will need to be tackled sooner rather than later. 

Whichever method of cleaning you choose, note that you may need to repeat it: very hard stains are rarely removed on the first go. You may also want to combine different methods to get the best results. 

Remember to wear gloves, don’t inhale any fumes and wash your hands thoroughly after you have finished cleaning the toilet. 

What Causes Black Streaks in the Toilet Bowl?

The three most common causes of black streaks in the toilet bowl are mould, mineral deposits from hard water and bacteria. Your black streaks can also be caused by a combination of these factors. 

If the water in your area is hard, mineral deposits will start to form in your toilet. Over time, they will go black, but can start out white or yellow. The most common culprit is the mineral manganese, but iron and calcium also do their bit .

Mould thrives in damp and dark places. Underneath your toilet rim is the perfect home for it, and you may have mould streaks in there that you have never seen and can’t reach when you clean your toilet. These stains can also be green and grey, even orange and red. 

If said mould starts spreading inside your toilet bowl, it’s time to do a thorough scrub and clean to get rid of it, as you don’t want it anywhere in your home. 

Bacteria can also cause black streaks in your bowl. Note that if you spot pink stains anywhere in your toilet or bathroom, you need to clean and disinfect your toilet immediately, as they are caused by a harmful pathogen called Serratia marcescens. 

Black stains above the waterline are most likely caused by mould, especially if they are originating from below the rim. Stains below the waterline are most likely limescale, caused by mineral deposits. You can remove them with a toilet cleaner or baking soda and vinegar, among other methods. 

How To Get Rid of Black Streaks in the Toilet?

There are many ways to get rid of black streaks in your toilet bowl, including natural cleaning agents and commercial solutions. 

Vinegar and Baking Soda 

Vinegar and baking soda are a cleaning mixture you can use for practically anything, from cleaning your toilet bowl to cleaning your sink, clothes and unclogging your bathtub. 

Drain the water from your toilet and pour a cup of baking soda in it. Chase it with a cup of white vinegar. Don’t be surprised by the chemical reaction, which will be quite violent. There will be a lot of bubbling and fizzing. 

Let the mixture do its magic for 30 minutes, then use a brush to scrub away the stains. Flush a couple of times.

You can use this method once a week to keep your toilet sparkling clean and fresh. 

Vinegar and Borax 

You can also mix vinegar with borax to achieve the same effect. Pour a cup of borax into a dry toilet bowl, and pour a cup of white vinegar after it. Let it sit for 15 minutes and scrub away with a toilet brush. 

You can also create a borax paste (fyi, you can do the same with baking soda). Mix it with some water until you get a toothpaste-like consistency. Wear gloves and spread it around the walls of the toilet. Use a handheld brush to scrub the stains, then let the paste sit for 30 minutes. Scrub again and flush. 

While you can’t buy borax in the UK, there are borax substitutes that work just as well. 


Bleach is a great toilet cleaner. All you need to do is pour about a cup into your toilet bowl, use a toilet brush to spread it to every corner and let it sit for 10-ish minutes. Then use the same brush to give the bowl a scrub and remove all the stains. Flush the toilet a couple of times to remove any bleach residue. 

This Harpic bleach is a great choice for your toilet bowl, as it also has baking soda, so your toilet will be crisp and white. 

Note that some toilet bowl manufacturers warn against using bleach on their products, as it can damage the material. 

If you have a septic system, never use bleach for cleaning your toilet, as it will kill all the good microbes in it alongside the germs and mould. 

Finally, never mix bleach with ammonia, as it will generate very dangerous, potentially lethal fumes.


No, it’s not a gimmick: Coke does a very decent job of removing stains, especially if they were caused by mineral buildup. All you need to do is pour the Coke onto the stains and let it sit for a couple of hours. Scrub away et voila!

You will need to use regular Coke. Sprite and Fanta don’t work, if you were wondering. This method also does nothing to disinfect your toilet, so you will need to do that bit with a different product. 

Tartar and Hydrogen Peroxide 

If you want to play chemistry class, you can also use Tartar cream and 3% hydrogen peroxide. Create a paste and place it on the stains. Let it sit for 30 minutes and then scrub it away. Flush to remove any residue. 

How To Remove Stubborn Black Stains From Toilet Bowl

The best way to remove stubborn black stains in your toilet bowl is to use a strong commercial toilet cleaner, designed specifically for limescale and mould buildup.

All of the above methods will work too, but you may need to repeat them several times. A commercial cleaner may not get rid of all the staining in the first go either, but it is usually much more effective, given its stronger ingredients. 

Harpic again has a great product for this purpose. You can also try this Dr.Beckman foam that does wonders. 

Why Get Rid of the Black Streaks in Your Toilet 

The black streaks in your toilet are not only ugly, they also pose a threat to your health, especially if they are caused by mould. Mineral deposits provide a good breeding ground for bacteria and mildew too. 

Mould spores can be very dangerous and can make you very sick, without you even realising. They can cause a runny nose, difficulty breathing, red and itchy skin, watery eyes. People who suffer from asthma or who are susceptible to mould allergies can have shortness of breath and even develop a fever. 

Untreated, exposure to mould can lead to further complications, especially if you keep inhaling it every day

How To Prevent Black Streaks in the Toilet?

To prevent black streaks in your toilet, consider a water softener. You can also use toilet bowl fresheners that treat limescale buildup, and of course, regularly clean your toilet.

You’d be surprised how much a weekly toilet scrub can help. The baking soda and vinegar method is simple and effective, especially if you repeat it on a regular basis. It’s gentle on the toilet, and is not harmful to your health. 

Buying yourself a toilet freshener will also deal with the mould and some of the stains. You already know I am partial to the Bloo Apple and Peach.

Finally, you can consider installing a water softener, but that will be an expensive undertaking, as manganese is notoriously difficult to filter out. Speak to a local plumber of water filtration company and see what kind of success they have had in the area. 

Wrapping It Up 

Getting rid of black streaks in your toilet will probably require a bit of scrubbing. The sooner you get down to it the better though, as you don’t want to give the stains a chance to really take a firm hold, as they will only get more difficult to remove the longer you leave them. 


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