Mold in Toilet Bowl Below Water Line | Why & Remove

Keep a burst of toilet sunshine is the most aristocratic thought for every homeowner. What if you find mold in the toilet bowl below the waterline, the tank, or behind the tank wall?

That is the most annoying part of any toilet- stains, overflow, and the toilet rings. The existence of mold throughout the entire house requires instant emphasis. 

The molds in the bowl can be an urgent problem. Even things in your household find the fastest way to get rid of mold in the toilet bowl.

The moisture, silt, and insufficient ventilation cause the black mold in your bathroom. Toilet molds are really a common challenge, and it is relatively simple yet fast to remove them. They have hair-like growth. If you don’t exclude them properly, they will come back.

Mold or mildew various shades, such as green or orange, may shift with time, but most of this is dark black.

Today’s focus is on -the reason behind mold growth and how to remove molds in the toilet bowl.

Can Mold Grow In Toilet Bowl Water?

Yes, Molds are love to grow in dark, dense, and humid places like toilet bol, siphon jets, etc. Human waste is the best nutritious food for developing molds.

Why Is Mold Growing In Toilet Bowl? 

Molds are generally a growth in moist places like toilets, bathroom drainage, bathtub, sink, and so on. They look like thin hair with a velvety touch.

Black molds or mildew growth several reasons

Reason1- Mineral Deposition 

Hard water consists of high concentrations of minerals like Calcium, Magnesium, and Iron, include some others. Prolonged inflation results in mineral deposition, and mold can thrive as a result.

Reason2- Stagnant water is responsible for mold growth.

Filthy water is the best atmosphere for mildew. They like dark, humid conditions.

The infrequent use of toilets is affected most by mold because of this.

In such a case, the toilet tank has microbial spoilage, the mold spores transfer towards the toilet bowl. Though, a moldy toilet bowl can exist without even a damp toilet cistern.

Reason3- Your Waste may be the Rason for Mold thrives.

A humid climate full of nutrition both are enough to grow microspores. 

Yes, the PH of urine and feces are the nutrients of Mildews.

According to research, molds prefer sugar as a food source, so diabetics’ toilets are particularly vulnerable to these microspores.

Reason4- Scratchy Porceline

We almost forget about scratches when comes to remove stains.

When those annoying stains happen, again and again, we use to remove them harshly even keep rubbing with a scrubber. That is absolutely not good.

Rubbing with a scrubber creates small dents in the toilet wall, which is one of the favorite places molds.

Another reason is if there is a crack present in toilet ceramic, then mold may harbor over there.

Reason5- Cause of mold growth below the toilet tank

If you notice- the molds are growing underneath the tank because the gasket/ seal washer shattered out.

The gasket protects from leakage when water passes through the tank to the bowl. If the gasket is thin and worn out, then the toilet is leaking while flushing.

Are you worried about how to get rid of molds, the process is simple yet easy. But whenever you may notice, take immediate action.

How Do I Get Rid of Mold in Toilet Bowl Below Water line 

Black mold is mostly present either below the water line or below the rim.

It is important that not just clean the affected area, kill the fungus too so they can’t grow further.

Option 1. Baking Soda+ Vinegar+ Bleach to Clean Toilet Bowl Below Water Line

Items you need for this-

  • Gloves
  • Mask
  • Toilet brush
  • Bleach
  • Baking Soda/ Borax
  • Vinegar in a Spray Bottle


Step1- Cleaning with toilet cleaner.

Wear the protecting gloves. Open all windows let the air ventilate. Before going for the main process shut off the water supply line and flush once. 

Add toilet cleaner and let it goes down the drainage.

Step2- Baking Soda+ Vinegar

Add cups of baking soda or borax over cleaner, spread over the waterline as well, even under the rim.

Add vinegar over the baking soda by a spraying bottle.

Cover the mixture all over the bowl wall, below the waterline, under the rim, etc.

Let it about 30 minutes to one hour so the reaction may diminish the molds as much as possible.

After an hour later, by using a non-corrosive brush, the all-over area gently.

Again leave it another 15 to 20 minutes. 

Now either turn on the water line or get a bucket of tap hot water and pour it directly into it.

Step3- Add bleach (optional)

If the mildew still exists after applying Baking soda and vinegar, you can add a small amount of bleach.

Add a small amount of bleach into the water at the present bottom of the bowl. ( use dilute bleach 1 cup bleach+ 1 gal of water)

Leave it another 1 hour, after the hour adds hot water.

This going to give you the ultimate result. If still present, repeat the process again but not add bleach.

Option 2. Hydrogen Peroxide for use to remove black mold in the toilet bowl

Hydrogen Peroxide is a great sterile agent. It has the potency to kill the microspore (Milds, Bacteria)

You need for the process-

  • Protecting gloves
  • Face mask
  • Hydrogen peroxide


  • Step1– Open all windows and make sure the room is well ventilated.
  • Step2– Confer half a cup of Hydrogen Peroxides into the bowl.
  • Step3– Use a toilet brush to spread the paint and make a good coat on the wall.
  • Step4– Cover the lid and leave it for 15 minutes.
  • Step5– After 15 minutes, gently brush the affected area ( underwater, under the rim).
  • Step6– Flush thoroughly.

Option3- Remove black spots (mold) in toilet bowl below the waterline By STEAM CLEANING

  • Step1- Take out your portable steam cleaner, connect the angular nose.
  • Step2– Turn on the steam cleaner with high pressure.
  • Step3– Hover the nozzle over the affected areas.
  • Step4– Add vinegar instead of water and spray over there.
  • Step5– This way, the dirt, and mold come out. Continue the process until the culprits are coming out.
  • Step6- After that, wipe out with the help of an old cloth or dry washcloth.

Those are the best process to get rid of black mold in the toilet bowl. 

How to Get Rid of Black Mold in Toilet Bowl Under the Rim and Rim Jets (VINEGAR+DUCT TAPE)

You can easily remove the molds under the toilet rim, but what about the rim jets or holes? Do you know, Mold can grow there also, create blockage?

The Ingredients needed for the process-

  • Vinegar
  • Duct Tape
  • Gloves
  • Old Cloth

Follow the Process-

  • Step1– Wear the protecting gloves. Turn off the water line to the tank.
  • Step2– Flush down once.
  • Step3– Dry out the bowl by using an old cloth. (especially the rim holes)
  • Step4– Take the duct tape and cover all rim jet ( according to size, you can use a scissor)
  • Step5– Check each hole may cover well by the duct tape.
  • Step6– Pour 1 gallon of vinegar into the tank.
  • Step7– Flush down, so all the fluid comes from the opening of rim jets and stays over there.
  • Step8– Leave it one and a half hours or overnight.
  • Step9– After the time pass remove all duct tape from the rim holes, allow all vinegar to come down to the bowl.
  • Step10– Take a wire or thin brush. Therefore you can rub it. Turn on the waterline.
  • Step11– Brush all over the bowl and pour a half bucket of water, next flush down.

Believe me. This idea is going to succeed. I already do it every alternate week to allow the inner clog to break down.

Read more– Easy and Effective alternative Methods to clean a Siphon jet.

How To Eliminate Black Mold in The Toilet Tank

Mold inhabitants in toilet tank too. When you’ve identified the mold in the water cistern, you must deeply clean the surface to remove it.

All you need-

  • A brush
  • Vinegar


  • Step1– Shut off the water supply line and flush it down.
  • Step2– If possible, remove all remaining water from the toilet tank.
  • Step3– Pour about one gallon of white vinegar.
  • Step4– Gently scrub the tank. Don’t rush there is lots of tiny fragile part present in the toilet tank.
  • Step5– Leave it for One and a half hours and after again brush the area.
  • Step6– Flush down the vinegar fluid.
  • Step7– Turn on the water supply line. After refill, the tank, flush one to two times so the remaining vinegar can all go down.
  • Step8– This way, you can exclude mold from the tank effectively.

If you notice the frustrating mold harbor behind the tank and tank wall.

Vinegar+ Bleach+ Baking Soda To Remove The Mold From Behind The Toilet Tank & Wall

Mold is so annoying it can grow everywhere, where minimum dampness and dark are present.

Besides bowl, under the rim, and toilet tank, sometimes they devour the back wall too. Though, it is not tough to remove from the wall.

You need the tools-

  • Baking soda
  • Vinegar
  • Spray bottle
  • Bleach
  • Gloves
  • Piece of cloth


Step1- Clean The Place

Wear the gloves and wipe out the area once by the cloth. Make the area a little dry so the paste can adhesive properly.

Step2- Make The Paste

Take one cup of Baking Soda and a half cup of vinegar, make a thick paste. ( adjust the quantity according to the area and paste consistency)

Step3- Apply and Rub

After making the paste, apply all over the affected area, make sure the paste covers the mold entirely.

Scrape the area with a hand brush. Leave for half an hour.

Step4- Wipe Out

Half an hour later, rub again and wipe out by rag. If needed, do the process again.

Step5- Spray the bleach as Disinfected

Molds are microspores. If you can’t kill them, they again grow from the same place two times more.

As a result, after removing mold, it is critical to spray disinfectant or bleach, hydrogen peroxide all over the areas to ensure that molds or bacteria can’t hover again.

Read More- How to Prevent Future Mold Growth in The Toilet Bowl

Final Words Black Mold In Toilet Bowl Water Line

Microspores are molds. If you don’t destroy them, they will sprout out of the same spot again.

As a reason, it is necessary to treat disinfect after eliminating mold to ensure that molds or germs do not reappear.

According to medical professionals, Mold contamination will cause a sinus infection, wheezing, reddish or irritated eyes and skin, seasonal allergies, and breathlessness.

It’s particularly awful for people with allergies to spores. It must be essential that you instated safety caution to prevent it from spreading.

Mold in the toilet is often easily removable with ordinary household remedies. 

If you doubt a major mold infestation in your toilet, contact a professional immediately.

FAQ1. Can Mold Make You Sick?

From an Expert Opinion, Mold can make you sick. Molds are hold spores that lead to severe allergic reactions like itching of the skin, redness of eyes, Feeling breathlessness, Fever, and so on.

Molds are far dangerous for people who have allergies, or hypersensitivity may lead to death.

FAQ2. Mold in toilet bowl diabetes- Any Relation?

Yes, It believes that Molds are love to eat sugary food. If you have diabetes, then mold may frequently occur because urine holds glucose.

A survey shows that people who have diabetics molds occur more frequently than those who do not.

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