Mold in Toilet – Prevention and Removal Guide [2024]


Updated on 04-Jan-2024

Mold is a type of fungus that can grow in various environments, including your toilet. It thrives in moist and humid conditions, making the bathroom an ideal habitat. While mold is not always harmful, it can pose a health risk if left unchecked. This guide will provide you with a comprehensive understanding of toilet mold, its causes, and the steps you can take to prevent and remove it.

What is toilet mold?

What is Toilet Mold - Prevention and Removal Guide [2023]

Toilet mold refers to any type of mold that grows in your toilet bowl or tank. This type of mold is typically black or green in color and can grow in a variety of shapes and sizes. It is often slimy to the touch and emits a musty odor.

Thus, hyphal fragments of prevalent mold species with strong pro-inflammatory potential may be particularly relevant candidates for respiratory diseases associated with damp/mold-contaminated indoor air.

Published in Indoor air | Citations: 9 | 2020

What causes mold growth in toilets?

Mold growth in toilets is caused by moisture buildup. This can occur for a variety of reasons, including high humidity levels in the bathroom, poor ventilation, and leaks or cracks in the toilet or plumbing. Other factors, such as infrequent use or cleaning, can also contribute to mold growth in the toilet.

What type of mold can grow in toilets?

A variety of mold species can grow in toilets, including Aspergillus, Cladosporium, and Stachybotrys (also known as black mold). These species are known to thrive in moist environments and can spread quickly if not removed promptly.

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Is mold in the toilet dangerous?

While most types of mold are not inherently dangerous, some can cause health problems if left unchecked. For individuals with mold allergies or sensitivities, exposure to mold in the toilet can cause symptoms such as coughing, sneezing, and runny nose. In severe cases, exposure to certain types of mold can lead to respiratory problems and other health issues.

What does mold in the toilet look like?

Toilet mold typically appears as dark, fuzzy spots or streaks on the sides or bottom of the toilet bowl. It may also grow in other areas of the toilet, such as the tank, under the rim, or along the base.

How to identify mold in the toilet


To identify mold in the toilet, you should look for the aforementioned visual indicators and pay attention to any musty odors that may be present. You may also want to perform a simple test by placing a piece of white bread in the toilet bowl for a few days. If mold appears on the bread, it is a clear sign that mold is present in your toilet.

How to prevent mold growth in the toilet

To prevent mold growth in the toilet, you should take the following steps:

  • Maintain proper ventilation in the bathroom by keeping the fan on and opening a window if possible.
  • Clean the toilet regularly and thoroughly, paying special attention to areas where mold is likely to grow.
  • Check for and repair any leaks or cracks in the toilet or plumbing as soon as possible.
  • Use a dehumidifier in the bathroom to reduce humidity levels.
  • Keep the toilet bowl and tank as dry as possible.
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How to get rid of toilet mold

To effectively remove mold from the toilet, follow these steps:

  1. Gather supplies: You will need gloves, a mask, a scrub brush, a bucket, water, bleach or vinegar, and baking soda.
  2. Ventilate the bathroom: Open a window or turn on a fan to provide proper ventilation while removing the mold.
  3. Turn off the water supply: Turn off the water supply to the toilet to prevent the mold from spreading during the cleaning process.
  4. Clean the affected area: Fill a bucket with a solution of water and bleach (1:1 ratio) or vinegar and baking soda (1:1 ratio). Use a scrub brush to clean the affected area, paying close attention to corners and under the rim of the toilet bowl. Let the solution sit for several minutes before scrubbing again.
  5. Flush the toilet: Flush the toilet several times to rinse the solution from the toilet bowl and tank.
  6. Dry the toilet: Wipe down the toilet bowl and tank with a clean cloth to remove any remaining moisture.
  7. Re-install the water supply: Turn the water supply back on and let the toilet fill. Check for any leaks or cracks that may have caused the mold growth and repair them promptly.

Repeat this process as needed until all mold has been removed from the toilet. If the mold persists or you notice that it has spread to other areas of your bathroom, consider hiring a professional mold removal company in Toronto for further assistance. Remember to wear gloves and a mask while cleaning mold in the toilet to protect yourself from exposure to harmful mold spores.

Toilet Mold – Frequently Asked Questions (FAQs)


Q: Why is there mold in my toilet bowl?

A: Mold in the toilet bowl is typically caused by moisture buildup and high humidity levels in the bathroom. Other factors, such as leaks or cracks in the toilet or plumbing, can also contribute to mold growth in the toilet.

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Q: How can I keep mold from growing in my toilet bowl?

A: To prevent mold growth in the toilet, maintain proper ventilation in the bathroom, clean the toilet regularly, check for and repair any leaks or cracks, use a dehumidifier, and keep the toilet bowl and tank as dry as possible.

Q: How to get rid of black mold under my toilet rim?

A: To remove black mold under the toilet rim, scrub the affected area with a mixture of water and bleach or vinegar and baking soda. You can also use a mold-specific cleaner designed for use in toilets.

Q: Can I flush mold down the toilet?

A: Flushing mold down the toilet may not completely remove it and could potentially spread it to other areas of your plumbing system. It is recommended to clean and remove mold from the toilet using the steps outlined in the “How to get rid of toilet mold” section.

Q: Can urine cause mold in the toilet?

A: Urine itself does not cause mold growth in the toilet, but it can contribute to moisture buildup, which can provide the ideal environment for mold to thrive.


Toilet mold can pose a health risk and should be removed promptly. By understanding the causes of mold growth in toilets, taking steps to prevent it, testing mold and removing it promptly when it does occur, you can keep your bathroom clean and healthy. Remember to clean and maintain your toilet regularly, keep the bathroom well-ventilated, and check for and repair any leaks or cracks to minimize the risk of mold growth in your toilet.


  1. Centers for Disease Control and Prevention (CDC) – Indoor Environmental Quality: Mold in the Bathroom
  2. Environmental Protection Agency (EPA) – Mold Remediation in Schools and Commercial Buildings
  3. Mayo Clinic – Mold exposure: Symptoms, treatment, and prevention
  4. American Lung Association – Mold & Your Home
  5. World Health Organization (WHO) – Home Indoor Air Quality: Mold