How to Clean A Toilet Tank Mold

Ever washed your toilet and you still perceive a bad smell that seems as if you didn’t wash the toilet well or makes it look like there is a part you missed out on? Then finding out how to clean a toilet tank mold is certainly a good idea.

The toilet tank is a major part of the toilet, the other being the toilet bowl. The tank is the upper part of the toilet that stores as much as two gallons of water.

What Are Molds?

Mold is a type of fungus which grows on different types of surfaces but it commonly grows on damp surfaces. Mold growth can occur in any room, as long as there is some form of moisture either from plumbing or increased levels of air humidity.

Bathrooms and toilets are places likely to have molds because they are always damp with lots of moisture.

Toilet tanks are usually covered. A dark and warm temperature environment ensues which is perfect for mold to thrive.

Also, toilets that are not flushed regularly are more likely to develop spores than regularly flushed toilets.

Toilet Tank Molds

Since the toilet tank is neglected most times when washing the toilet, there is an eventual accumulation of dirt and debris-free water in the toilet tank. This leads to the growth of molds and other mineral deposits.

Why is mold growing in the toilet tank?

Mold is growing in the toilet tank because of infrequent use. Also, the temperature of the toilet tank is always warm. This is a perfect breeding ground for the growth of mold. Hence, there is a need to clean the tank periodically.

If you notice that mold is growing below the toilet tank, it means the washer is worn out. The washer is not sealed effectively and hence water will drip out running along the bottom of the toilet tank. In this case, it is important that you replace the washer to fix this problem.

What Are The Effects Of Molds On Us?

Molds can cause numerous health conditions. Being exposed to mold either through touch or through inhalation can lead to coughing, sneezing, wheezing, or congestion of the nose.

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It can also induce asthma symptoms in people with that condition and cause health complications for people with compromised immune systems or existing health issues.

Molds are a danger to health and have to be removed immediately.

How to Clean Toilet Tank Mold

To clean a toilet tank, the following materials are needed:

  1. Rubber gloves
  2. White Vinegar
  3. All-purpose cleaner
  4. Scrub brush with plastic bristles


The first step is to put on your rubber gloves. The gloves serve as protection from germs and chemicals.


Next, open the toilet tank and pour as much vinegar as possible. It could be as much as three gallons depending on the size of your tank.

Vinegar is used here instead of bleach as bleach is corrosive and can affect other parts of the tank.


After that, allow the vinegar to stay in the tank for at least five minutes to work on discoloration, the residue at the bottom of the tank, and mineral deposits and molds that have built up over time.


After waiting for about five minutes, flush the toilet at least twice to remove all the vinegar that is present in the tank. Ensure you flush till all the vinegar is removed.


The next step is to turn off the water supply. In order to do this, find the water valve. It is usually on the wall or close to the base of the toilet. After finding the valve, close it.


After that, lift the toilet tank lid and flush the toilet until the water drains completely.


After the water has drained completely, apply the all-purpose cleaner and scrub inside of the tank. Using the brush, ensure you scrub all the major parts of the tank thoroughly, leaving no part untouched.

We recommend you use a new brush instead of the brush already in your toilet so that you would not introduce germs.

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Ensure you use a scrub brush with plastic bristles with a shape that would allow you to get to different corners without stress.


Turn on the water valve and flush the toilet again until the water in the tank and bowl is clear.

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Video: How to Clean A Toilet Tank

Watch this video for a visual representation of what to do:

Ways To Prevent Mold In The First Place

The best method of dealing with mold is to prevent them. Ensure you clean your toilet regularly at least once a week using an anti-fungal spray.

As much as possible, reduce moisture in and around the toilet and bathroom. A shower fan can be installed in the toilet to reduce moisture.

Other alternatives include opening the window or using a dehumidifier. Also, ensure that plumbing leaks are repaired as soon as they are noticed.

If you think there is any leak anywhere around the bathroom or toilet, fix it or call a plumber as soon as possible.

You can also install tank insulation to keep the tank water cool. Tank insulation provides a layer between the walls of the tank and the air which is outside the toilet.

How to Clean A Toilet Tank Mold – Related FAQs

What Can You Do To Make Your Toilet Tank Smell Better?

Here’s what you can do to make your toilet tank smell better:

  1. Locate the pipe supplying water to the toilet.
  2. Turn the water supply valve clockwise or tie the toilet’s float if your toilet doesn’t have a shutoff valve. 
  3. Flush the toilet to remove some water from the tank.
  4. Pour ½ cup white vinegar and baking soda into the toilet tank.
  5. Drop 2-3 aspirin tablets or denture tablets into the tank. Leave for 15-20 minutes to dissolve.
  6. Use a bristle brush to gently scrub the toilet tank sides.
  7. Turn on the water supply to the toilet tank.
  8. Flush the toilet 3 or 4 times.
  9. Light a scented candle or a match in the bathroom to fix the odor in the toilet.  

Why Does Your Toilet Smell Like Poop?

The following are reasons why your toilet smells like poop:

  1. Blocked drain. This prevents solid things from flowing through the drain except water.
  2. Broken wax ring. A broken wax ring occurs when the rings are worn out after a long time.
  3. Filled septic tank. This can occur when the toilet tank is filled with solids.
  4. Sewer roof vent is blocked. An indication of this is a gurgling sound or slow drainage.
  5. Dry P-trap. This can happen if the toilet or bathroom is not used regularly.
  6. Blocked tub drain or shower. This can be caused by hair, rust, dirt, and other deposits.
  7. Dead animal. A dead lizard in the toilet can cause the smell.

What Is The Brown Sludge In Your Toilet Tank?

The brown sludge in your toilet is called iron bacteria. They are a group of bacteria that depend on Iron oxidation for energy. Examples of these groups of bacteria are Gallionella and Leptothrix. They can cause harm to your water treatment machines and home. 

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Other forms of iron bacteria are the acidophilic iron bacteria like Ferrobacillus ferrooxidans. Iron bacteria build up in toilet tanks because of the presence of water. They are either brown, orange, or red in color.

When they feed on Iron in the toilet tank water, the dissolved ferrous iron will oxidize with oxygen to form rust-colored iron oxides or ferric iron. As the cells decay, they release the brown slime you see in your toilet tank.

How Do You Get Rid Of Algae In Your Toilet Tank?

To get rid of algae in your toilet tank, do the following:

  1. Turn off the water supply valve to the toilet and flush. 
  2. Sponge water out of the toilet tank.
  3. Wear your goggles, mask, and rubber gloves.
  4. Spray the toilet tank sides with concentrated chlorine bleach and scrub with a toilet brush. 
  5. Turn on the water valve and allow the toilet tank to get filled, then flush.
  6. When the toilet tank fills up again, pour one cup of chlorine bleach into the water.
  7. Leave it to sit for about 10-15 minutes and flush.
  8. Fill the tank half brim and fill it up with muriatic acid. 
  9. Allow the acid to sit for 15 minutes. Flush 10-20 times to dilute the acid in the drain.

Why Is Your Toilet Tank Not Filling Up?

The following are reasons why your toilet tank is not filling up:

  1. The float ball is too low. To fix this, adjust the float arm such that the float ball goes up.
  2. The fill valve is closed or blocked. Adjust the screw clockwise to allow the water flow in.
  3. The trip assembly is blocked or improperly positioned. Inspect the trip assembly and either fix or replace it altogether.
  4. The water pressure could be low. This could be as a result of rusted or leaking pipe preventing strong flow of water into your home.

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