A toilet bowl that doesn’t look impeccably clean when you notice black streaks in toilet? This part of the toilet may need to be cleaned every day, depending on how often it is used.
However, even with regular cleaning your toilet bowl may not look as good as expected. This can make you wonder what causes black streak in toilet bowl.
But before solving this problem, let’s see exactly what these black streaks are.
What causes black streaks in toilet bowl?
There are several things that can cause that stubborn black streak in toilet bowl:
Mold thrives in dark, damp areas, and your toilet bowl is one of those places. Mold streaks are usually found in the underside of the toilet’s edge. You may fail to reach that spot during regular cleaning and mold will develop in time. Our advice is to remove mold immediately to prevent it from spreading. 
Bacteria can cause black streaks in your toilet bowl as well. Regular cleaning should help.
Warning: if you see pink-colored streaks in your bathroom or toilet bowl, sanitize thoroughly immediately. A harmful bacteria called Serratia marcescens is an opportunistic pathogen with antibiotic resistant properties. It is known to cause pneumonia, urinary tract infections, and wound infections.
- Mineral deposits
Black streaks in toilet can have less hazardous causes, yet the phenomenon is still very annoying. Most commonly, the issue is caused by hard water containing small particles of minerals. These minerals cause water lines where the flow is strongest. In time, they can cause larger buildups.
One of those minerals is manganese, which is responsible for most of the black staining.
Manganese is a beneficial substance and we need it as part of a healthy diet, in limited quantities. However, your plumbing systems and bathroom fixtures don’t really benefit from it.
People living in certain parts of the United States may deal with this issue. For instance, the Midwest is known for having elevated levels of manganese in the soil. The excess manganese can reach tap water and well water.
Tap water containing too much manganese can have an earthy or metallic taste. High levels of manganese are risky for your nervous system. At the same time, you will experience staining in areas which have contact with tap water.
Why get rid of black streaks in your toilet?
Black streaks in toilet bowl are not only unsightly, but can also represent a health hazard. Even if the streaks are caused by mineral buildup, they are holding moisture and can cause mildew to form.
Mold in buildings and homes is quite common. Mold spores can enter your home through clothing, shoes, and pets. Once it reaches a damp spot in a warm and dark place, mold grows.
Exposure to mold can cause various health problems, with some people being more sensitive to mold than others. Common symptoms include a stuffy nose, wheezing, and red or itchy skin and eyes. People suffering from asthma or mold allergies can have more severe reactions, such as fever and shortness of breath.
How to get rid of black streaks in toilet?
There are multiple ways to eliminate black streaks from toilet bowl.
Keep on reading to find out how to get rid of black streaks in toilet:
- Method 1 – bleach
Pour one cup of bleach into the toilet bowl. Stir it around using the toilet brush, scrubbing away the black lines inside the bowl. Wash the entire surface of the bowl.
Let the bleach rest for 10 minutes. The waiting time is necessary in order to entirely eliminate the black mold and the stains. Flush the toilet once or twice until no residue is left.
Warning: First of all, never mix bleach with ammonia. The chemical reaction between the two substances generates dangerous, potentially lethal fumes.
Secondly, make sure you don’t lose warranty of your toilet bowl due to using bleach. Some manufacturers clearly indicate you should not use chlorine to clean their product. Check the instructions before using bleach.
- Method 2 – vinegar and baking soda
If you don’t want to use bleach and prefer a homemade solution, you can try vinegar and baking soda. Sprinkle 1 cup of backing soda into the toilet, followed by 1 cup of vinegar.
Don’t use large quantities of vinegar and baking soda as the solution could overflow the toilet.
Let the mixture work for 30 minutes.
Lift the lid and scrub the toilet bowl with a toilet brush. The scrubbing process should be easy after the ingredients have broken the residue apart.
Flush the toilet until the bowl is clean.
Repeat every week.
- Method 3 – borax and vinegar
Method 3 uses borax and vinegar to get rid of the most stubborn stains.
Add 1 cup of borax into the toilet bowl and some vinegar over it. Scrub the toilet and let the mixture work for 15 minutes.
Scrub again and flush the toilet.
An alternative is using a borax paste you can prepare by mixing borax and water. Put some gloves on and spread the paste onto the walls of the bowl. Scrub stains and streaks with a hand brush and leave it for 30 minutes. Scrub again gently and flush the toilet.
- Method 4 – Coke!
Did you know that Coke is very effective at cleaning objects around your house? Coke is also good for removing stains inside the toilet bowl, especially mineral buildup.
Pour the soda onto the stains or spray it in a light coating all over the toilet bowl.
Let the Coke sit for several hours until it dissolves the black streaks. Scrub the stains away and flush.
Remember that Coke is only affective at removing grime and stains. If you want to disinfect the toilet, you will still need a disinfectant cleaner.
- Method 5 – Iron OUT
Iron OUT Automatic Bowl Cleaner is one of the best-rated products for cleaning your toilet bowl. It is specially formulated to clean rust stains from your toilet, but it repels hard water as well. After each use, Iron OUT prevents stains from forming for up to 45 days.
Being effective against iron also makes it effective against manganese, so you will kill two birds with one stone. The product is easy to use, as you just need to drop the table into the toilet tank. It is the perfect product for regions with hard water and high iron/manganese.
Extra tip: if the streaks are very stubborn, use a pumice stone that is safe for porcelain bowls. These products are naturally abrasive and will remove the most stubborn stains and buildups.
How to prevent black streaks in toilet?
Cleaning your toilet bowl insistently is not a solution when the cause is not eliminated. If the quality of water continues to be poor, the problem will persist. The right thing to do is improve your tap water quality.
- Filtering your tap water
If the cause of your problem is a high level of manganese, you can prevent black streaks by filtering your water.
The best way to go is consulting a water treatment expert. Manganese filtering is notoriously difficult and a standard water softener will have little to no effect. More than that, manganese can cause most water filtering systems to malfunction.
The expert will most likely conduct a water test. If high levels of manganese are found, the most effective solution may be an iron filter. This is because iron and manganese are similar from a chemical point of view.
- Using toilet bowl fresheners and deodorizers
A simpler and more affordable solution can be using a toilet bowl freshener. Most households have this, whether it’s in the form of a clip-on freshener or gel discs. All these solutions help cleaning stains and prevent minerals from building up on your toilet bowl walls.
There is also the option of toilet tank deodorizers, which help breaking down waste and paper too. However, some plumbers advise against this type of deodorizer. Apparently, the chemicals in the product can affect the rubber flap inside the toilet tank.
If the rubber flap starts to disintegrate, you will see loose rubber particles. They could contribute to those black streaks instead of preventing them.
Looking to have an impeccable home? A sparkling clean toilet could be the one missing piece of the puzzle. Want to know how to get rid of black streaks in toilet? By applying our solutions and preventative measures, your toilet bowl will look as good as new!