Why You Should Never Use Bleach for Mould Removal
Published on May 28, 2017 | Updated - Jul 18, 2025
For decades, bleach has been the go-to solution for getting rid of mould. In fact, many cleaning websites still recommend it.
But here’s why bleach is not the answer to effective mould treatment.
Why doesn’t bleach work on mould?
Bleach will recolour mould and leave behind a ‘clean’ smell, so you think the job is done. But don’t run off to the beach to enjoy the weekend just yet. All that you’ve done is take the colour out of the mould. Unfortunately, the mould membrane is still hiding underneath the surface, emitting mould spores and is likely to appear on the surface again very quickly, which is very frustrating!
Interesting fact: In 2012, Choice magazine awarded Exit Mould a “Shonky” award because the product is based on chlorine bleach, which recolours the mould instead of killing it.
Why is mould so bad for your health?
While mould certainly looks unattractive, it can actually be detrimental to your health.
Some mould species produce mycotoxins, which are toxic to humans and can cause hay fever-like symptoms, and respiratory illness and may even inhibit your body’s immune system.
People with weakened immune systems and with chronic lung diseases are more at risk of mould infection.
RECOMMENDED READING
The Magic Bathroom Mould Cleaner You Can Make YourselfHow can I treat mould?
Small mould patches can be effectively treated with one of these non-chemical solutions that are each proven to kill over 90% of mould types. Once the mould has been killed, we recommend using sugar soap to treat the mould stains, or if you wish, use a bleach or chlorine based product (please use googles and a mask).
1. The Vinegar Solution
Vinegar is well known for effectively treating mould.
Use a spray bottle with a diluted white vinegar solution (2 parts water and 1 part white vinegar) and apply liberally onto the area. In areas of heavy mould, use a soft-bristled nylon brush to agitate the mould.
Leave the vinegar on the mould for an hour to work its magic. Re-spray with your diluted vinegar solution and wipe away the mould with a clean and slightly damp cloth.
2. The Tea Tree Oil Solution
Tea tree oil has amazing anti-fungal properties, and it will effectively treat mould. However, it’s not such a great cleaner. We recommend using a 3% tea tree oil solution consisting of 1 teaspoon of tea tree oil and 2 cups of warm water. Shake well before using.
Combine the solution in a spray bottle and apply it to the mould-affected area. In 20 minutes, lightly sponge off the mould with warm water. If the stain mould remains, treat it with vinegar (see the above solution).
3. The Clove Oil Solution
Clove oil can also be an effective mould treatment.
Put 1/4 teaspoon of clove oil into a litre of water and pour into a spray bottle. Lightly mist onto the area and leave it overnight. Wipe down with a 1:1 white vinegar and water mixture.
A couple of things to remember about clove oil:
-
It can be toxic when ingested by humans and pets, so take care.
-
Follow the above measurements closely, as too much can discolour surfaces.
If the Mould Stain Remains
The solutions above will effectively kill the mould but may not remove the mould stain. To treat the remaining mould stain we recommend:
- Sugar soap diluted in warm water. This is our preferred option as it’s safe and quite effective
- Chlorine based mould treatment products such as Exit Mould. Whilst these products aren’t good at killing the mould, they are good at treating the stain. When using these products take care to ventilate the area (we recommend using a respirator mask) and use a drop sheet as these products will bleach fabrics).
How to Treat Mould for Large Infestations
If the mould-affected area is bigger than 1 square metre, it is probable that the mould is growing in hard-to-reach places like wall cavities.
A major mould issue will need remediation by professionals Electrodry Mould Cleaning, which can treat the mould and the mould spores the infestation produces.
It is worth noting that while a professional can treat the mould, you will also need to treat the source of the moisture (such as leaking pipes or a roof issue) that is causing the mould.
Your mould removal expert could provide some general advice, but you will need to engage the services of a builder or plumber to identify the source of moisture to ensure the mould does not come back.
Your mould removal expert may provide general advice, but you will need to engage a builder or plumber to identify the moisture source to ensure the mould does not return.
