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Have you opened your toilet tank and discovered that black mold is growing inside? If so, keep reading because I’m going to show you how to remove black mold from your toilet tank easily and effectively.
When we first moved to Japan, we did a lot of research on what we needed to know about the country.
We thought we had it pretty well covered, but one thing we hadn’t accounted for was mold growth inside our house.
Japan can get very humid in the summer. The combination of high humidity (moisture) and darkness is the perfect breeding ground for black mold which is why I was shocked and disgusted to open my toilet tank after six months of living in Japan and discover that it was covered in black mold.
Fortunately, a small amount of black mold like this is easy to remove and doesn’t generally require you to call in a professional mold removal company.

Is Black Mold In Your Toilet Tank Dangerous?
Mold comes in a variety of colors, but black mold seems to be the one that strikes fear in the heart of people who find it in their homes.
The truth is, mold is all around us – even in the air we breathe.
And while you certainly don’t want mold growing in your toilet tank (or anywhere in your home), black mold has never been proven to be more dangerous than any other type of mold (1).
Mold of any color can cause certain health issues in some people, including headaches, itchy eyes, dizziness, fatigue, and nausea (2).
Infants, children, the elderly, and those with underlying health conditions are most likely to suffer health issues from mold exposure.
However, many people have no negative effects.
Finding black mold in your toilet tank isn’t necessarily a reason to panic, but it does need to be removed.
How to Remove Black Mold From Toilet Tank
If you’ve discovered black mold in your toilet tank, here’s what you need to do.
Step 1 – Put on a pair of rubber gloves and a disposable face mask. Switch on your bathroom exhaust fan and if your bathroom has windows, open them. While black mold exposure isn’t as toxic as you may have been led to believe, it’s still important to have good ventilation when you’re dealing with mold and chemicals.
Step 2 – Remove the lid of the tank from your toilet and place it on a hard surface (inside your bathtub or shower is a good option).
Step 3 – In a spray bottle, prepare a bleach solution of 1 part bleach and 2 parts water.
Step 4 – Spray the bleach solution all over the toilet tank lid and inside the toilet tank. Spray the solution directly onto the visible black mold and all over the inner tank and lid, as there may be small mold spores growing that you’re unable to see.
Step 5 – Let the solution sit for 10 minutes. After 10 minutes, check to see if there is any remaining mold. If there is, spray a small amount of bleach solution and use a hard-bristled brush to scrub the mold off.
Step 6 – Rinse the inside of your toilet tank and lid with water. Return the lid to the tank and flush the toilet to drain the tank.
How to Clean Black Mold From Toilet Tank Without Bleach
If you’d prefer not to use bleach, you can remove black mold from your toilet tank using white vinegar instead.
Bear in mind that white vinegar will take longer to remove mold than bleach, and you may need to use a little more elbow grease.
If you choose to use white vinegar, repeat steps 1 and 2 above.
Step 3 – Fill a spray bottle with undiluted white vinegar.
Step 4 – Spray the white vinegar all over the toilet tank lid and inside the toilet tank. Spray directly onto the visible black mold and all over the inner tank and lid, as there may be small mold spores growing that you’re unable to see.
Step 5 – Leave the vinegar for one hour, then scrub the area to remove any remaining mold.
Step 6 – Rinse the inside of your toilet tank and lid with water. Return the lid to the tank and flush the toilet to drain the tank.
How to Prevent Black Mold From Growing In Your Toilet Tank
A toilet tank is the perfect breeding ground for black mold – dark and damp.
Unfortunately, this means that the usual recommendations for keeping mold at bay – keeping the area dry and well-lit – can’t really be implemented.
If your toilet tank is prone to growing black mold, the best way to prevent this from happening is to spray a bleach solution on the inside of your tank once every week or two.
I’ve been doing this since I first discovered black mold in my toilet tank, and I have never had another instance of black mold in my tank.
References:
- https://www.cdc.gov/mold/stachy.html
- https://www.epa.gov/mold/mold-and-health