Does Bleach Kill Mold?

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Categories Cleaning Mold
Learn if bleach is a mold-killer in this guide.

Finding mold growing in your home can be a jarring experience. What now?

Killing mold is a concern for so many people since it can cause structural damage. Worse still, mold can be harmful to those with allergies and weaker immune systems (1).

Bleach is known as the ultimate mold-killer. If you’re hesitant and don’t know if this is the right course of action, keep reading and find out when bleach is the solution for you and when you should use another product instead.


Does Bleach Kill Mold?

Mold can appear anywhere, provided there is moisture. It can grow on walls, floors, carpet, appliances, or furniture. You’ll most likely find mold in kitchens, bathrooms, laundry rooms, and basements.

The key to controlling mold is to eliminate residual water and humidity. If you already have mold at home, you need to kill it and fix the moisture problem. That way, it doesn’t come back (2).

Bleach is marketed as one of the best solutions against mold. However, this may not be the best for all surfaces. Therefore, look at the surface first and check whether it’s porous or not. If it is, then you should not use bleach.

Why Does Bleach Not Kill Mold on Porous Material?

Bleach is effective in some cases, but not when it comes to porous surfaces. Not only does bleach fail to kill mold on a porous surface, but it can also make matters worse.

Porous areas have tiny openings (pores) in which the mold grows. The water component of the bleach will penetrate these pores and can increase mold growth.

At first glance, you would think that you’ve killed the mold, but on the contrary, you’re essentially feeding it. The correct way to kill mold in porous materials such as wood and drywall is to use distilled white vinegar and hydrogen peroxide.

Is Bleach or Vinegar Better to Kill Mold?

Both vinegar and bleach can kill mold. But if we were to answer which one is better, we would say vinegar. In fact, vinegar can kill the fungus on both hard surfaces and porous surfaces and will terminate the mold at the root.

It’s important to keep in mind that bleach can only kill mold on dry surfaces. So if you’re doubtful about which kind of surface you’re dealing with, we advise you to go for the vinegar.

Also, if you’re looking for a non-toxic way to remove mold, consider using vinegar as it’s mildly acidic. When it’s combined with baking soda, it can be very powerful.

Should You Use Bleach to Kill Mold?

You might be surprised to learn that many of your household cleaning products contain some level of bleach. Stain removers, toilet cleaners, and even tile residue removers all use bleach.

Bleach is very effective when it comes to killing bacteria. Unfortunately, it has adverse health issues, especially when used carelessly.

If you have a respiratory condition, you may suffer when exposed to the fumes of bleach. Some people reported feeling nauseous, having coughing fits, and a painful sting in their nose and eyes when using bleach (3).

Bleach is harmful on its own, but when combined with other chemicals from other cleaning products, it can become even more hazardous.

Mix with Caution

You should never combine bleach with ammonia as it can produce toxic fumes. Avoid mixing bleach with products such as drain cleaners, window cleaners, and dishwasher detergents.

Bleach is also very bad for your pets. It can cling to your pets’ paws and fur. Unfortunately, when licking themselves, they will ingest the harmful chemical.

So if you have a bird or a small pet, it’s best not to use bleach. Even the smallest inhalation of bleach fumes can result in them becoming very sick (4).

Is There Another Way to Kill Mold?

You may want other non-toxic ways to kill mold without endangering your health and the health of your loved ones. Here are some of the natural methods we recommend.

Try Vinegar

As we said, vinegar is one of the most effective, natural, and non-toxic methods to kill mold.

In a clean and dry spray bottle, pour some distilled vinegar. Spray the moldy area and let the vinegar work its magic for one hour. Proceed to clean the area with water and let the area dry.

Hydrogen Peroxide

Hydrogen peroxide has properties that kill bacteria, viruses, and fungus.

Pour hydrogen peroxide (3 percent concentration) in a spray bottle. Spray abundantly on the mold area and leave for 10 minutes. Then proceed to clean the area with a scrub brush and then wipe.

Baking Soda

Known also as sodium bicarbonate, baking soda can be used to kill mold. It’s a safe, natural option.

Take a spray bottle filled with water and add a quarter of a tablespoon of baking soda. Shake the bottle until the baking soda dissolves completely. Spray the moldy surface.

Proceed to clean the area with a scrub brush and then wipe. Spray the area again and leave it dry to prevent the mold from returning.

Types of Bleach to Kill Mold

Both chlorine bleach and oxygen bleach can kill mold, but they are totally different.

Chlorine bleach uses a solution of chlorine and sodium hypochlorite — also known as caustic soda (5).

Most household detergents that contain chlorine will be labeled as “laundry bleach” or “bleach.” As a chemical substance, chlorine is approved by the EPA and the U.S. Department of Agriculture. It’s used in sterilization and safe food production.

Chlorine bleach, on the other hand, is a potent disinfectant used to prevent germs from spreading. Still, the EPA doesn’t recommend using it as a solution to kill mold (6).

Chlorine bleach is a highly toxic chemical that releases harmful substances.

It also lingers in water, and when it accumulates, it becomes harmful to aquatic life.

Meanwhile, oxygen bleach is a biodegradable, eco-friendly sanitizer that is as effective as chlorine bleach (7). It is made out of sodium percarbonate which dissolves in water and becomes water, oxygen, and sodium carbonate.

It’s a non-toxic, colorless, odorless formula that can be purchased as either a powder or a liquid.

How to Kill Mold Using Bleach

Have you decided which method and which type of bleach you want to use? Now, we’re going to tell you how to kill the mold effectively.

First, here are some precautions you should consider:

  • Be safe: make sure to protect your hands by wearing gloves, so the bleach doesn’t contact your skin. Put on a mask, eye goggles, and old clothes that you won’t mind staining.
  • Open windows and doors: Bleach produces harmful fumes, remember.

How to Kill Mold Using Chlorine Bleach

If you’ve picked chlorine bleach, follow these steps:

  1. Mix it up: Combine a cup of bleach to a gallon of water. The ratio of bleach to water is one cup bleach to 10 cups of water. If you have a large surface, you can calculate the quantity accordingly.
  2. Prepare the solution: Pour the mixture into a clean, dry spray bottle.
  3. Let it sit: Spray the mixture on a moldy surface and let it rest. How long will depend on the surface and the severity of the mold, but at least 30 minutes is necessary.
  4. Scrub if needed: If the surface is rough or irregular, you can scrub the area with a bristle brush.
  5. Rinse and dry: Rinse the zone with plain water and let it air-dry.

How to Kill Mold Using Oxygen Bleach

Most oxygen bleach detergents come with an instruction manual on the packaging. You will be able to remove the mold successfully if you follow these steps and respect the mentioned quantities:

  1. Prepare your solution: Add the oxygen bleach powder to warm or hot water for better dissolution. The ratios are as follows: ⅕ a cup to 1 cup per gallon of water. Pour the solution into a clean, dry sprayer.
  2. Spray and wait: Spray the solution on the moldy area and let it rest for 15 minutes.
  3. Rinse and dry: Rinse the area vigorously with water and then wipe it.

You can also use a scrubber, cloth, or sponge instead of a sprayer and follow the same steps.

How to Prevent Mold in the Future

Panic over, the mold is gone, but you don’t want a recurrence. Mold will occur wherever there is water damage, such as leaks or flooding.

When water damage occurs, make sure to fix it promptly and dry thoroughly after fixing it. Here are some recommendations that you can follow to minimize mold from occurring:

  • Avoid humidity: Keep the humidity as low as possible (30 percent to 50 percent) all day long. You can do this by using a dehumidifier or an air conditioner.
  • No carpets in wet areas: Don’t put down carpets or many rugs in rooms or areas where there is excessive water usage: bathrooms, laundry room, basements.
  • Ventilate: Ensure there’s good ventilation in your house. Make sure vents are installed in the kitchen and bathroom.
  • Fix water leaks: If you notice water leaks in walls, pipes, roofs, or even plant pots, try to fix them immediately or call a maintenance company. Dry the affected area directly after fixing the problem.

Mold Be Gone!

Mold is an issue that lots of households suffer from. It’s a subject that annoys many homeowners, and it can affect the residents’ health.

You can combat mold with bleach if you are dealing with non-porous surfaces. Vinegar is excellent for porous surfaces.

Want to opt for other natural, non-toxic solutions? You can use hydrogen peroxide, vinegar, and baking soda, which are also very effective.

If the mold is widespread and severe and these home remedies do not work, take the next step. Call a mold removal specialist who will test the mold and find the optimum way to terminate it.

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About the Author

Matthew Sullivan

As a writer with keen interests in DIY and HVAC, Matthew has always found great pleasure in taking things apart and learning how to put them back together.
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