Nobody imagines their bathroom becoming a breeding ground for fungi, but that’s what happens when we postpone the cleaning for too long. Regular mould is nuisance and easy to remove, however, if you spot or smell black mould, that’s when you need to take action right away.

So, if:

  • Your ceiling has become darker in certain areas
  • You recently moved into a new home and you start to see black spots starting to form around your tub or sink
  • Black spots appear even after renovation of some of the bathroom items
  • A property you own has developed black mould after the last tenant moved out

Then read along.

Table of Contents:

What is black mould?

This type of mould, known also by its Latin name Stachybotrys Chartarum, should not be underestimated. Unlike the regular strain of mould, this one is slimy in appearance. It’s also greenish-black and sometimes slightly grey in colour. The appearance isn’t what should worry you, but rather what it does.

Black mould releases trichothecene mycotoxins. These neurotoxins can result in the need for serious home repairs, but the bigger problem is how dangerous they are to humans.

Exposure to black mould can result in a number of negative side effects with varying degrees of severity. These include:

  • Dizziness
  • Tiredness
  • Headaches
  • Hallucinations
  • Allergic reactions (sneezing, coughing, watery and itchy eyes, runny nose)

When spores are inhaled for a longer period of time, some of these symptoms may occur:

  • Nausea
  • Skin irritation
  • Asthma
  • Lung infection
  • Bleeding in the lungs
  • Swelling of the lungs

Black mould in the bathroom – causes

This type of fungi germinates in very specific conditions which, sadly, are often times found in your bathroom. Perfect conditions for black mould growth include:

  • Poor ventilation – it makes it hard for humidity to escape, resulting in moisture build-up and wet areas stay wet for a longer time.
  • Condensation – when warm air gets in contact with a cold surface it becomes water drops. This adds to the next condition.
  • Humidity – black mould needs about 90% humidity to start growing. This percentage is not hard to reach when you have condensation and poor ventilation in a room.
  • Warmth – black mould can grow in different temperatures, but does it best when it’s warm.
  • Darkness – it doesn’t need light to grow, in fact, large quantities of light can actually kill this fungus.
  • Oxygen – like all living beings, this one needs oxygen as well. However, it won’t die even if you manage to deprive it of oxygen. It will go into a dormant state until it senses oxygen again. This dormant state can last quite a few years.
  • Time – Normal fungi only need from 24 to 48 hours to start growing whereas these need several days (8 to 12).

Your bathroom isn’t the only room where this fungi can spring up. Intense rains or floods often times result in water leaks inside walls, under floors and above ceilings. These leaks then become the basis for the development of the right conditions. Since there is no way to spot the leaks right away, the fungi have plenty of time to feast and grow uninterrupted until it’s ready to release spores to further expand itself.

How to get rid of black mould in the bathroom

There are several areas in your bathroom which are prone to black mould growth because they collect the most moisture. These include:

  • Tile grout
  • Shower tiles
  • Window sills
  • Around sinks
  • Bathtub
  • Ceiling

You’d either notice a slimy and muddy residue on the surfaces or you’d pick up a musty smell with your nose. If you happen to find black mould in your beloved bathroom, do not panic. There’s still hope, but you have to act quickly while the amount is still small enough. You can tackle the problem by using either commercial cleaners or natural means.

Do not to scrape away the mould as that will make it release its spores into the air in the form of fine dust. The spores will make it difficult to breathe and might even trigger an asthma attack if you already have this illness. With that said, always wear protective gear such as gloves, goggles , and a face mask.

Commercial cleaners


Mix one part of this almighty compound with 4 parts of water, after which apply to the nasty black mould, using a spray bottle. Bleach is really strong even when diluted with water, so it will instantly kill the nasty fungi. Keep in mind that this substance can damage paint, if that’s where the mould is located. Always test the chemical on a small spot to see its effects before going all the way.

Mould eradication kits

You’d find countless different brands both online and offline. Whichever one you choose, the important thing to know is to always follow the instructions on the packaging. Some of these kits come with their own protective gear and include several products which are used one after the other in a strict order. You have to be very careful when using this kind of strong chemicals.

Anti-bacterial sprays

Usually these are not bleach-based, so they won’t damage any paintwork, hopefully. Anti bacterial sprays are easy and quick to apply, but might not be able to remove any mould stains. The good thing is, they are great to spray every once in a while, to make sure the fungi will not return.

Never mix any of these commercial cleaners with one another!

Natural non-toxic cleaners

Tea tree oil

By mixing tea tree oil with water, you’ll be able to spray the mixture onto the spores. Once the mixture has set for several hours, you should be able to scrub away the mould. If you finish the tea tree oil, complete the job using baking soda. Read about tea tree oil and fungal contamination.

Vinegar and baking soda

Pour white distilled vinegar in a spray bottle and do not dilute it with water. Spray it over the mould and wait from 30 minutes to about an hour. After that, spray some baking soda mixed in water. Scrub until all the spots are gone and rinse with clean, warm water. The smell of vinegar will fade away after several hours. Hydrogen Peroxide can be a substitute to vinegar, but it needs to be mixed with water.


Mix equal parts of ammonia and water in a spray bottle. Spray the black mould and wait several minutes for the solution to work its magic. Afterwards, use a brush to clean the area. Repeat if necessary.

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Maintenance tips – how to prevent black mould in the bathroom

The best way to protect yourself from the wretched black mould is to never allow it to develop in the first place. Since that option is not always available, the best you can do is to follow these maintenance tips, so, hopefully, you’d never have to deal with this fungus again.

  • Wipe down wet surfaces after bath time – this will remove any leftover moisture from tiles, grout and bathtub. Also wipe down the shower curtains if you have any.
  • Don’t leave any wet damp towels on the floor – it’s easy to just leave the towel on the floor after you’ve wiped all the water drops, but don’t do it, because that towel will hold moisture and contribute to the problem.
  • Keep your bathroom well ventilated – after each bath or shower, keep the ventilation fan working for at least 30 minutes. If your bathroom has a window, even better, keep it open. The steam needs to escape from the bathroom.
  • Fix leaks as soon as they happen – minor leaks might be an inconvenience which can wait another day, but they do attribute to more moisture in your bathroom.
  • Keep rugs dry – if you happen to have any rugs in your bathroom, make sure they are always clean and dry.

Hire a professional cleaner

If you feel the task of black mould removal is too tiresome or time consuming for you, you can always book a regular home cleaning session with Fantastic Services. The professionals we work with will have your bathroom looking like new and no black mould will threaten you or your family any longer.


Always be on the lookout for mold, especially the back type. Always remember to:

  • Wipe down your bathroom after shower
  • Ventilate as much as possible
  • Fix leaks as soon as they appear


Have you ever had black mould in your bathroom? How did you get rid of it? Let us know down below, so we can start a conversation.

  • Last update: February 6, 2020

Posted in Cleaning Guides

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