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Does Bleach Kill Mold?


If you have mold and are thinking that you can just use bleach to get rid of it, think again. It can kill some types of mold on surfaces and usually only in small amounts. We’ll explain that more in detail below. Also, mold doesn’t grow only on the surface. The chemical properties of bleach prevent it from penetrating where it needs to go. Oh, and it’s noxious to breathe and burns eyes and skin.

Bleach does strip the color out of the mold, so it will look cleaner, but it does not actually kill most mold. It looks like it does, but it doesn’t. Mold is a microbe, so to kill it you need a strong antimicrobial. Some people are convinced that it’s the best product to use for removing mold. It’s hard to convince them otherwise because it looks like the mold is gone. Just like when you use bleach to remove a stain on your clothes, it removes the discoloration caused by mold, but not the mold itself.

Have you ever noticed that no matter how many times you clean those annoying mold spots in your bathroom shower or tub, they come back later? This is why. Bleach is sodium hypochlorite, a strong oxidizer. Mold is a microbe, so killing it requires a strong antimicrobial. Mold digs in and infiltrates the material itself, so the mold you see on top is the tip of the proverbial iceberg.

The Clorox Company hired a third-party firm to conduct studies to test its performance. Spore Tech Mold Investigators did the testing. Here’s what the report says. “…liquid bleach mixed at 3/4 cup of Clorox per gallon of water will be effective against hard, non-porous surfaces against… Aspergillus niger and Trichophyton mentagrophytes (commonly known as Athlete’s Foot Fungus)”.

Of note here, that they specific “non-porous surfaces” and only two types of mold. Black mold (stachibothris) and other more dangerous types were not included in the study. OSHA is actually the first federal agency to begin changing its recommended use of bleach for mold removal. We hope that other government agencies will follow soon.

Bleach not only won’t kill most mold infestations, but it’s unpleasant to smell and, in high concentrations, can be unhealthy to breathe. Check the back of your bleach bottle. That hazard warning label is there for a reason. Every time I enter a home or business where they’ve just tried to use bleach to remove mold and I get that first whack of it in the air, I want to lose my lunch. That stuff is nasty.

Using bleach to kill mold is like trying to kill a tree by snipping off the top. Mold remediation pros use antimicrobial treatments that not only kill microbes, but that can also penetrate into materials to kill off the roots of the mold.

Do you have a mold problem that you can’t get rid of? Give us a call. We’re happy to help.