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How Can You Get Rid Of Black Streaks In Toilet?

Note: This post may contain affiliate links. This means that at no cost to you, we may receive a small commission for made purchases.

Our toilets are fantastic at taking care of business… you know the kind I mean.

However, even though they’re highly capable of discarding all the nastiness that we put in them, and a toilet brush can deal with any residual mess, there’s one thing that often has both our toilets and us stumped.

I’m talking of course about the black streaks you’ll find lining or gathering deep in the bowl.

Thankfully, these can be removed, but before you gear up and go guns blazing into the stinky abyss, it helps to understand what the black streaks are and what causes them.

What Exactly Are Those Black Streaks In Your Toilet?

There are actually a number of ways these irritating black streaks can develop in your toilet bowl, so let’s address the usual suspects one by one and see if we can’t find out which is to blame for your toilet bowl woes.

Mold Madness

The most common cause of a black-streaked toilet is mold, and it’s no surprise really. Mold absolutely adores moist, covered areas, and a toilet fits that bill to the tee. 

You can usually tell if mold is indeed the culprit by the location of the black marks. If they’re higher up on the bowl, just beneath the lip of the toilet, then 9 times out of 10, you’ve got yourself a mold issue.

Due to these sorts of stains being partially covered by the lip of the bowl, even if you clean regularly, they’re easy to miss, and you often won’t even realize they’re there until the mold spreads further down the basin.

To prevent this from happening, give the non-visible spots of your toilet the same TLC you give the parts that are on show.

But not to worry if you didn’t catch it and the mold is now visible. A quick cleaning session will solve the problem.

Bacterial Bonanza

Bacteria are another cause. Many different kinds will cause dark streaking, and while this is irritating and unsanitary, it’s actually the lighter streaking you need to be warier of.

Pink streaks are usually caused by a bacteria known as Serratia marcescens, an insidious pathogen that can survive antibiotic intervention.

It’s known to infect wounds, cause urine infections, and can even trigger a bout of pneumonia — clean it as soon as you see it!

Mineral Deposit Dilemma

Not all black streaks in your toilet are creepy living organisms whose only purpose is to cause havoc; sometimes, they’re just a consequence of the water conditions in your area.

Toilets in hard water zones are vulnerable to this form of staining, as hard water has heavy mineral content.

Dissolved in hard water, you’ll find numerous particulate minerals, such as calcium and manganese.

But before you recoil in horror and start panic-buying bottled water, you should know that hard water isn’t necessarily bad for human consumption, but it certainly isn’t great for your plumbing, as mineral content deposits will build up over time.

The mineral content of hard water will be deposited in water line patterns running all the way down the bowl. These lines indicate areas where the flush flow is strongest.

You may also notice staining in your sinks and around your faucets. If you’re uncomfortable consuming hard water, don’t worry, you don’t have to move house; just invest in a water filter. I’d recommend this filter for your shower, and this one for your faucet.

Do You Really Need To Get Rid Of The Black Streaks In Your Toilet?

While black streaks in your porcelain throne aren’t necessarily always a health hazard, it’s still important that you remove them before they get out of hand.

Regardless of risk factor, it’s a good idea to get rid of black streaks simply to keep a clean and hygienic household.

I don’t know about you, but I don’t want my guests to have to glare into a black hole of doom every time they need to powder their noses. I don’t want it for myself or my family either.

Granted, hard water marks aren’t dangerous to us, but mineral deposits get worse over time, which can play hell with your plumbing, so it’s best to nip the issue in the bud.

Besides, just because some of the streaking is caused by hard water, doesn’t mean it all is.

When it comes to mold and bacteria, it’s even more important to take action, as these organisms are a health hazard.

Mold inside the home is perhaps more common than a lot of people realize, as spores can easily snag on pet fur, shoes, or clothing fibers and infiltrate your living space.

Should these spores find a nice dank place to settle, they start germinating like rabbits (so to speak), and exposure to the resulting mold can trigger a variety of health issues.

The biggest worry is for those with asthma (like myself) or allergies to mold, as they will experience more serious reactions.

They may exhibit feverishness and trouble breathing on top of more typical reactions, such as a blocked nose or itchiness of eye and skin.

Time To Get Rid Of Those Black Streaks In Your Toilet

How Can You Get Rid Of Black Streaks In Toilet?

I know this post has been all doom and gloom thus far, but fortunately, there are numerous ways you can tackle the issue in question. 

Read On For 5 Black Streak Removal Methods!

Method 1: Good Old Fashioned Bleach

Bleach is an absolute beast for removing these nasty dark streaks from your toilet bowl (see also ‘Toilet Bowl Smells Like Urine‘).

All you have to do is measure out a single cup of bleach then drizzle it around the top edge of the bowl so it cascades down and gets good coverage.

If you need to, use a clean toilet brush to spread the bleach to all the problem areas. 

After application, leave it to rest for at least 10 minutes then give your toilet a couple of flushes to rinse both the bleach and the residue away — good riddance!

Do bear in mind, however, that you should never combine bleach and ammonia, as the pair create potent toxic fumes.

What’s more, if your toilet is still under warranty, check with the manufacturer that using bleach won’t void the coverage.

Method 2: The Home Remedy (Baking Soda and Vinegar)

If you’re looking for a less harsh, home remedy that still packs a punch, powder your toilet bowl with a cup’s worth of baking soda, then pour in a cup of vinegar.

Spread the solution around the bowl with a clean toilet brush then leave it to work its magic for about half an hour.

After, give the bowl a good scrub with your toilet brush and flush a couple of times.

Method 3: Borax Blast

This is the same as method 2, but you use borax (see also ‘Borax In Your Pool: How & When To Use It‘) powder and vinegar instead of baking soda and vinegar. The only difference is that you probably only need to let it rest for 15 minutes as opposed to 30.

If you want to omit vinegar from the equation, you can make a borax paste out of borax powder and water.

Once the paste is ready, don some protective gloves, then spread it all over the toilet bowl.

Follow this up with a good scrubbing using a hand brush you don’t mind getting rid of, let it rest for 30 mins, scrub once more, and flush your problems away!

Method 4: Have a Coke!

The fact that Coke Cola can strip away stains is pretty damning in terms of our own consumption of the soft drink, but it’s a godsend for our spring cleaning.

All you have to do is pour your Coke over all the problem areas, kick back for a couple of hours, then return, scrub, and flush — easy!

Do bear in mind, though, that Coke isn’t a disinfectant. It only aids with the cosmetic side of things.

Method 5: Bring Out the Big Guns (Iron OUT)

Iron OUT is the number one toilet bowl cleaner, and I can’t speak highly enough of it.

Not only will it tackle black streaks, but rust stains too. It’s effective at removing manganese and iron, meaning hard water lines don’t stand a chance.

But as great as Iron OUT is, I’d pair it with a disinfectant to make sure all the nasty germs are being removed along with the stains.

Something like this toilet-safe pumice cleaner may also be a good call if you’ve got some particularly stubborn stains to battle.

Black Streak Preventatives

To combat hard water streaks, the best preventative is to invest in a filter designed specifically for the job. Unfortunately, whole house filters can be expensive, but they’re a worthy investment.

That said, before you buy anything, I’d suggest consulting a water treatment professional, as manganese can be tricky to filter.

A much cheaper solution that can help keep both stains and bacteria at bay is a toilet freshener, but there’s no substitute for a consistent toilet cleaning schedule.

Final Thoughts

There you have it, folks — you no longer have to be embarrassed by your toilet. Try one or more of these methods, and you’ll have a sparkly white bowl in no time.

Keep up with your standard maintenance, and you may never have to deal with black streaks ever again!

author avatar
Anthony Barnes
Anthony Barnes is the founder of Water Heater Hub and a second-generation plumber by profession. Before developing Water Heater Hub, Anthony Barnes was a full-time plumber, and he has undertaken a wide variety of projects over the decades. As a second-generation plumber, it was easy for Anthony to get used to the technicalities of all from a tender age


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