Should You Use Bleach To Clean Mold?

Cleaning mold with bleach spray

Why using bleach to clean mold may not be a good idea.

Hello, my name is Cheryl Ciecko of I’m the founder and a licensed architect, who specializes in water damage, mold and healthy buildings.

Bleach has been listed in a lot of documents by the EPA, by the American Wood Council for cleaning wood, and a lot of government agencies and product manufacturers actually mention using bleach.

Most of this information has been outdated and is no longer recommended.

It doesn’t mean that it wasn’t recommended at one time, the EPA did recommend using bleach at one time, but they’ve updated their advice, wisely, and they no longer recommend that.

Some of these other websites, or organizations, are following information that they got long ago, and they haven’t noticed that there’s been a change.

When the EPA changes their recommendations, they don’t put a flag up and say; Yeah, we made a mistake and we don’t recommend what we used to recommend.

So we end up with these remedies, that are actually unsafe, being passed down over the years, because they haven’t been researched again for the updates.

Bleach is highly toxic in and of itself. Bleach itself is about 97% water and 3% hydro sodium chlorite, which is the toxic part. The bad news about that is that the bleach component, which is only 3% of what’s in a product, or in a gallon of bleach, evaporates very quickly, the water does not. When that bleach evaporates out of the water very quickly, it does nothing to the mold spores in the air. The mold spores are actually feeling threatened and they’re going into the air and they’re now looking for wet places to land.

Well, the area’s just been wet with the water component of the bleach, and the bleach is evaporating out of it so quickly that there’s not a lot of cleaning going on. While the surface may look clean, because you’ve used bleach, usually bleach is soaking into porous materials and drenching the roots of whatever it was that you removed on the surface, that now looks clean. But those roots have gotten a big drink of water and they’re going to come back bigger and better than they were in the past.

So, know that many, many of our building materials are porous. That means they absorb water. Wood, concrete, brick and masonry, all are porous and absorb water. That means they will be soaking in the water.

You might clean the surface with the bleach, but the bleach is now evaporating, it’s actually very toxic for human beings to be breathing, and it does nothing to the mold in the air. The mold spores that are flying around the air, panicking because they’re being attacked, now have lots of wet places to land, and the roots of the mold that might’ve been removed on the surface are getting a great big drink of water. So that’s a reason to not use bleach for cleaning on any kind of porous surface.

Wood, dry wall is another porous surface, concrete, brick and masonry are all porous, they absorb water and they are not a good place to use bleach.

So use other options. There are quite a few, and I talk about them in a variety of places.

I always suggest non-toxic solutions that won’t harm the person using them, and won’t leave a residual off gassing smell that could harm people over time. So keep that in mind, we don’t want to harm people with the products that we’re using to actually remove something that’s already harmful.

I hope this is helpful on not using bleach. Anybody who’s recommending that may be a good person, they may be very smart, they’re just following outdated information. Check out my other blog post on the topic to learn more.

Cheryl Ciecko is an ALA, LEED AP, Licensed Architect who helps homeowners and building professionals create safe homes through online education to prevent mold, water damage, and poor indoor air quality. 


You can find her video masterclasses, online programs, and education subscription options at .


For detailed answers on your specific situation or building project, schedule your appointment for an individual consultation.




The information contained in this presentation is for educational purposes only and is not intended to diagnose, prescribe, treat, or cure any disease, ailment or injury to the body. It is not medical advice. FDA regulations prohibit the use of medical claims in conjunction with the sale of any product not approved by the FDA. Statements made herein have not been evaluated by the FDA. 

Any products, techniques, and/or personal usage tips referred to are not suggested as a replacement for proper treatment from a licensed health care professional. I am not a licensed health care professional and the decision to use or not to use any of this information is the sole responsibility of the listener and/or reader. Everyone is an individual with different body types, different blood types, different body chemistries, and it is important to remember that what works for one person may not work for another person.