When faced with a mold problem, you may be tempted to reach for the bleach. It’s a common household product and probably something you already have in your home. But does bleach kill black mold, especially on porous surfaces like wood and drywall?

Mold is a common problem that can be found in many homes. There are different types of mold, some of which are more harmful than others. Black mold is a type of mold that can be particularly dangerous. If you have black mold in your home, it is important to get rid of it as soon as possible. In this guide, we will answer the question: Does bleach kill black mold?

What is a bleach solution and what does it contain?

A bleach solution is a mixture of chlorine bleach and water. The concentration of bleach in the solution can vary, but it is usually around five percent. The main ingredient in bleach is sodium hypochlorite, which is a strong oxidizing agent.

When mixed with water, it forms hypochlorous acid, which is responsible for the bleaching effect.

What are some common uses for bleach?

Bleach has many household applications. It can be used to disinfect surfaces, clean laundry, remove stains, and kill mold. It is important to note that not all molds are killed by bleach. 

Does bleach kill black mold?

Bleach is effective in killing microorganisms, but not all of them. It kills some, but not others. When applied to a surface containing black mold, bleach will kill the mold that it touches, but unfortunately, nothing else.

What it does not do is kill the spores that are present in the surrounding air, which is a critical aspect of mold remediation.

Although you may be able to kill existing black mold with bleach, there are several reasons why it should never be used for this purpose:

It’s not effective against mold spores

When you’re dealing with mold growths on surfaces such as walls or tiles, you’re also dealing with millions of airborne spores that have been released into the atmosphere. These spores are what spread the mold from one location to another and are the reason for such a rapid growth of colonies.

Bleach is not effective in killing mold spores. In fact, it can actually help them to spread. When the bleach solution dries, it leaves a residue behind that is attractive to mold spores. They will land on the surface and begin to grow again.

It’s toxic

Chlorine bleach is a very harsh chemical that can be dangerous if not used properly. It can cause skin irritation, respiratory problems, and even death in high doses.

It’s corrosive

Bleach is also highly corrosive. It can damage surfaces such as wood, metal, and rubber if left in contact for too long.

It creates hazardous fumes

When mixed with ammonia (another common household product), bleach forms chlorine gas, which is a hazardous chemical. It can cause respiratory problems, skin irritation, and even death.

It’s flammable

Bleach is also highly flammable. In the presence of an ignition source, it can easily catch fire and result in a dangerous blaze.

So, does bleach kill black mold?

The answer is yes, but with caution. While using bleach can help to remove surface mold in certain instances, it’s ineffective at killing mold growing in porous materials.  It may be able to kill the mold that it comes into contact with on a surface, but it will not kill the spores that are present in the air, which is critical for remediation.

Bleach is also toxic, corrosive, and creates hazardous fumes. For these reasons, it should never be used to kill black mold. There are safer and more effective alternatives available, such as vinegar or borax. If you are dealing with black mold, it is best to call a professional who will have the proper equipment and know-how to use it safely.

How do you now get rid of the mold?

Mold remediation can be a tricky business. It’s not enough to simply kill the black mold that you find in your basement or attic, for example. Killing mold with bleach and other household cleaners only addresses the symptom, not the moisture problem that allowed it to grow in the first place.

The best way to handle a black mold problem is to attack it at its source. Here’s how to do that:

  1. Find and fix any leaks or water issues causing black mold spores to grow.
  2. Clean up any excess water or moisture, and dry the affected area completely.
  3. Scrub away any visible mold growth with detergent and water, and dry completely.
  4. If the area is too large to handle on your own, or if you prefer not to use bleach or other harsh chemicals, call in a professional mold remediation company.



While bleach may be effective in killing black mold, it is not a recommended method due to the many dangers it poses. There are safer and more effective alternatives available, such as vinegar or borax. If you are dealing with black mold, it is best to call a professional who will have the proper equipment and know-how to use it safely.