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cleaning mold with bleach

3 Reasons Why You Should Never Use Bleach To Clean Mold

Mold is not a topic that most homeowners want to think about. If they are discussing mold, it is likely because they have discovered some mold in their home, and as it can be both dangerous and costly, the chances are if you have found some you are desperately trying to determine how to get rid of it as soon as possible.

You may be wondering if you can do the remediation yourself and if so, what type of chemicals or cleaners you should use. Luckily for you, we’re here with those answers!

Bleach is NOT the answer for many mold issues

Be honest. What is the first chemical that comes to mind when you think of cleaning up a mold problem? Is it bleach? Chlorine bleach is often regarded as the answer for removing and halting mold growth and is, as such, usually the first thing many reach for when cleaning a mold contaminated area. Yet while bleach may be effective in certain applications, it will not exonerate mold on a porous surface and can actually contribute negatively to certain mold problems. This blog post will explain three reasons why bleach should not be used to combat mold and give better alternatives for you to choose from if you have a mold problem in your home.

Bleach loses effectiveness over time

Chlorine bleach rapidly loses its effectiveness. If you leave a glass of chlorinated water out on the counter for a few days, the chlorine will evaporate – even within the container. This evaporation process indicates that it will be hard to ascertain the true potency of your chlorine bleach solution as the chlorine can escape through plastic. It may have been sitting at the store, or in your home for some time, diminishing the ability to perform.

So, if you don’t know how old your bleach is (or you happen to know that it is fairly old), your cleaner may not be effective at all. What may end up happening is that the older bleach will only partially kill the surface mold and create a bigger mess than you already had.

Bleach does not kill mold on porous surfaces and can actually contribute to mold growth!

If you read the label on your bleach bottle, you will probably see that it is only designated for non-porous surfaces. This means that chlorine bleach can only kill surface mold. Because mold can grow deep roots within porous surfaces, such as wood and drywall, bleach will not assist you in exterminating mold. As the chlorine cannot penetrate to destroy the growth at its roots, therefore, it remains on the surface while the water component of the bleach reaches further, which can actually feed the mold growth. So, if you want to completely eliminate the mold from your home, bleach is definitely not the answer. The worst part is that you may think you have completely eliminated the mold when, in fact, you haven’t.

Bleach is toxic

Chlorine bleach produces fumes that pollute the air and can become harmful to both humans and pets. Chlorine bleach also generates a by-product called dioxin, which is linked to cancer. Used over time, bleach builds up these pollutants in the environment. As we’re sure you’ll agree, the last thing you want to do is create more toxic chemicals in your home – mold is toxic enough!  There are many safer alternatives which are also much more effective at getting rid of mold.

So, what should you use to kill mold?

There are many considerations that need to be evaluated when determining whether you should clean up the mold yourself or hire a professional. Always do your research and choose wisely. Sometimes DIY mold removal ends up being a bigger headache than it is worth and can actually cost you more money in the long run.

If you have ascertained that it is safe to clean up the mold yourself, there are a variety of options available. The most important step is to determine the cause of the moisture and make any necessary changes to assure that mold will not return and the area is properly ventilated. Some issues will need to be resolved by cutting out the moldy material and completely replacing it. This will make sure that the mold roots are removed and will not return.

You should also  consider testing  to determine what type of mold you are dealing with as that may help determine what type of chemical you may need to remediate it. There are a variety of mold test kits you can buy, or you can have a professional test it for you. Some types of mold and mildew are easier to get rid of than others.

Some people use vinegar, borax, hydrogen peroxide, tea tree oil or ammonia to kill mold, especially on small areas and non-porous surfaces, as well as sanitizing mold and  mildew on clothing. More specific biocides may be needed if you are dealing with a porous surface that you cannot remove, such as wood framing.

Safety first

Proper treatment for mold growth will depend on the surface it has populated. Always consult a professional before attempting to remediate a mold problem yourself. If you don’t have experience with mold remediation the EPA recommends that any mold problem larger than 10 square feet be examined by an expert.

Mold is a serious issue and should be taken seriously. There are many potential health concerns associated with being exposed to mold and if you have a mold issue in your home, you shouldn’t take the remediation lightly. Consider calling in a professional mold remediation company or a mold expert to advise you on the best course of action. If you do decide to clean up the mold yourself, research and do your due diligence before choosing a chemical to clean it.

Brian and Krystle Reeves manage, a website dedicated to providing a place to share and receive information that will better allow individuals to fight and conquer toxic mold and the consequences of mold exposure.

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37 thoughts to “3 Reasons Why You Should Never Use Bleach To Clean Mold”

  1. Thank you so much for this! We’ve always used bleach for mold clean-ups and this is very good information to have! We will have to be more careful from now on.

  2. It is such a common misconception. We didn’t realize either, until we started looking into it!

  3. We tried using bleach on sub flooring and drywall in a fixer to kill mold and it never worked. We had to cut it out completely and replace.

  4. Our daughter was planning to use a basement room for her adult daughters bedroom but discovered mold.She is on limited income and believes she can remove the mold herself. Are there any organizations who could help her achieve this at a greatly reduced cost so the space could safely be used in the basement

  5. I just set off 3 Mold Bombs..I was treating with bleach and though it seemed to work before my kept returning in small spots..was wondering if I should spray or paint the wood beams in crawlspace as well?

  6. What happens if I thought I got rid of all the mold and take care of repairs only to have the mold come back where I can’t see? Will it destroy the home? Will it be unhealthy to live in?

  7. I have a tenant moving in and there is mold on much of his furniture including his mattress. He’s cleaning thnigs off with a bleach and water solution. How can I convince him that he needs to replace this stuff? How do I show him that he is contaminating a previously non-mold environment?


  9. I have been given a building that it would cost me 12 to $15,000 to build , I have seen obvious signs of mold on a wall . Built as a one room 30′ x 30 ‘ room ,recently added wall through center ,being on a low set income retirement ,it is tough to think of scrapping a perfectly great shop building ,which otherwise I can’t afford to build ,and will never be able to have one ,so if anyone can advise me on this only two year old structure ,it will be greatly appreciated . Thanks , TIM


  11. How do I get all of the mold spores out of the air after I removed the source? Also does anyone know what I can use on my cat’s mold rash that is safe and natural? Your help would be greatly appreciated. Thank you.

  12. When killing mold on porous surfaces like drywall and wood, I use Concrobium at Lowes, there are other out there as well. This usually does not remove the discoloration, it not designed for that, because of it’s non-toxic nature. I use it on the job when I see mold. Get it nice and damp, not to wet and it should be go to go. If you need to get rid of discoloration and your not painting, you could try bleach after the mold killer has all dried, then reapply mold killer after wards

  13. So true. Moisture is the culprit. Any attempts of cleaning mold without addressing moisture and leak issues will not be successful long-term.


  15. I am a little confused by the title of this article “3 Reasons Why You Should Never Use Bleach To Clean Mold”- “20 thoughts on 3 Reasons Why You Should Never Use Bleach To Clean Mold”. The article breaks down different reasons why Bleach is toxic and overall, ineffective at permanently eliminating mold. Along, with the complexities- involving size of space with mold contamination and the type of material contaminated (from porous services, paper,wood, fabric, drywall, etc), making Bleach a dangerous, unreliable, mainly ineffective substance to combat mold; yet, people’s responses often talk about using bleach, either conveying it as a viable option and/or flat out suggesting the use of bleach in particular circumstances. The comments come across as if people have completely ignored the article’s professional advice. I am confused. After reading this article about why Bleach should not be used to eliminate mold (one of numerous articles I have read that reinforce the same advice), I am walking away with the understanding that bleach is not a wise approach when attempting to remove mold- DIY. I personally wouldn’t play around trying to eliminate mold, as a lay person. Mold and its spores attach to one’s clothes, are inhaled, and if the contamination is considered large enough- Professional Remediation is the recommendation, and certified companies must follow strict guidelines for mold removal. People who think DIY- I would think it’s important to know what amount is considered large, regarding mold contamination. Don’t assume safety or diminish the possibility one’s mold problem could be serious or dangerous, (to do DIY). I am not a person who fuels scares about mold, or whatever theories exist about Black Mold. I just think mold is not something to blow off, perceived as “just a mildew-type thing”, not dangerous, etc. My belief is that one address mold contamination, of any size, with research, and safety in mind.

  16. I am working on a job where the gutter down pipe ended right next to an outside corner and water found its way into walls through the siding. I pulled siding and found a mix of black and a ring of live spores embedded into drywall. KT covered about 15 s.f. so what I did was cut out drywall And used HEPA filter vac to clean up. And then I use vinager to clean all areas that were in with mold then spray peroxside on all and let air dry 24 hrs then rebuild

  17. I use trisodium phosphate & distilled water, then bleach and distilled water, more phosphate, acetic acid (vinegar), then I run over the whole thing with borax, or Boraguard termite & mold inhibiting treatment, then a borate/borax infused paint product specifically made for mold treatment. I have hot and cold foggers that will saturate an area with a alkali fog of borax or borate compound in water vapor or steam. I have used pelletized dry ice to remove the mold itself. That procedure is similar to sand blasting, but the dry ice is solid CO2 which is sublimated so it goes straight from pellets to a gas, and the sand, so to speak, just evaporates away. After that you really really need to run over everything with a borate mold inhibiting paint, or wood treatment. Citrus terpenes work well too. These would be orange peel oil, or lemon peel oil. You may not want to use these on woods you might want to stain or paint in the future.

  18. Just using the chlorine bleach is not a solution you can use other natural ways to remove black mold which definitely stop the growth of toxic black mold otherwise that black mold will reappear again and again. You can use tree oil, grapefruit, vinegar, baking soda etc which is a natural remedies and prevent black mold. You cna just go through these simple steps to clean Toxic black mold.

  19. Any thoughts on my shoe closet where the shoes repeatedly grow small gray spots I presume are mold? Would placing a closet fan help with circulation as I keep my windows open all the time but live near the beach in San Diego.

  20. So instead of spraying a little bleach and rubbing, I should remove my entire back door, replace it and just hope the mold stays away?

    This is interesting advice.

  21. I did a lot of research on this, and the one thing I found out. Mold likes the same conditions we do. It needs organic food (like drywall, wood, etc), It needs water (high humidity usually), and a temperatures between 40 and 120 degrees F, tho it can survive lower and higher temps (but not below freezing for long, and generally not above 160 F) Removing the water is the best solution in most cases. Then use one of those products like Concrobium. But remember, it has a survival instinct. As soon as it is threatened by any kind of contact it releases spores. This includes spraying it with bleach. The only way I know of to slow that down is put a tent over the infested area and vacuum out the air through a filter to outdoors. There are over 5000 species of mold, 70+ of “black” mold. Some of these are linked to respiratory problems.

  22. My husband’s shower constantly has mold in the grout. There is a river rock floor with mold between the rocks. I have been spraying with bleach but it keeps coming back. Now I understand why. It is nearly impossible to keep moisture away. . We do have an exhaust fan and keep it on sometimes. We also live in Florida. Replacing the shower is not an option. Should I spray with vinegar and baking soda. How long will it take? I have read much on better. Some send conflicting. Help please.

  23. As a certified mold remediater using the best chemicals designed for such an event is always recommended first. The job however delights in its own unique experiences and golden rules. First rule when you’ve found mold, look everywhere else too. It’ll be in the craziest places but it follows water and everything in your home soaks up water. Always double check.
    This bleach issue is missing vital information. When bleach dries it leaves chlorine crystals behind. The second water hits it again, its liquid bleach again. Bleach will soak into any service that water can it just might have to sit a little longer for some things. When it dries and leaves crystals they no longer smell but you shouldn’t be breathing that dust so the surface will have to be wiped again if people or pets use that area.
    But, cleaning up mold is usually only a part of keeping mold from coming back. Some demolition may be required. Sanding and caulk, foam and sealers may also help. Mold can be easy just make sure to prevent any water in the future from collecting. That goes for the air as well cause, its water too. Good luck ?

  24. WE have a small cement block house we just rehabbed. We took out all of the dry wall in the bathroom and replaced it with hardyboard and then tiled the entire bathroom in the process the shower tub knob and other fixtures were replaced. the tub faucet was left loose and leaking dripping some. I think the renter may have removed it to tighten it and took out the o ring- seal. This caused water to be pushed into the wall and into the adjoining utility area and other half bath. We were not told about it until I went over and discovered mold on the dry wall in the utility room. I thought is was due to a water hose being left on from a spot in there. When I was there removing the dry wall I saw water come out of the back wall from one of the renters taking a shower. That is when I called the plumber to find the leak. He did stating there was no O ring in the fixture crimp in the cooper pipe from over tightening he thought. When I examined the inside of the bathroom I discovered mold in the grout and rust was on the new shower curtain rod. The other half bath had wainscoting and this showed blackened areas as well as warping. When I asked why they did not let me know there was a proublem they said they just noticed it. I believe this proublem occurred 11 months prior to my discovery. So we have attempted to spray under the tub and get the areas the sprayer will reach but the tiled walls and also the walls on the other bathroom have been exposed. for a long time. The new stainless steel appliances have some surface rust as well. My concern is if now throughout the entire house including the attic and ac ducts. We just finished spending 45,000 renovating this house new tile floor electric out lets ac new roof new fixtures doors new bathrooms and kitchen. I am terrified this can not be fixed or the cost will be too expensive to repair. this was our 401k . what should I do I got insurance on the house but it only was insured 2 months ago due to the insurance co demands for an updated water heater the one thing that we hadn”t replaced. So I am afraid if I submit a claim they will say it was pre exsisting. It may have been Even if we are able to claim it our deductible is 1,000. I am just sick over this mess. What should I do.

  25. Bleach will kill mold on non porous surfaces just fine. Use a ratio of one cup to a gallon of water. As for the rest of this, buy a new bottle of bleach and either use outside or air the room out as you would for any other chemical. Telling people not to use bleach is just ridiculous. I have years of fire, water, and mold remediation and am IICRC certified. We use bleach to clean mold from many surfaces.

  26. Many interesting comments on this article to be sure! Thanks for pointing out that bleach is Not the best cure for mold and is a hazard in and of itself if used improperly and especially with no or poor ventilation. There are many industrial mold and mildew products, many are considered “green” now and are very useful.

  27. This comment section is hilarious! The article everyone is commenting under plainly says to not use bleach on porous surfaces like wood, drywall, etc., because the mold has membranes (i.e., ‘roots’ that extend into the pores, and bleach only chases it back into those pores, then gives it the water component of bleach to actually feed it! The article says use 5-6% vinegar, people! Or hydrogen peroxide, borax, tea tree oil, etc., but vinegar would be cheapest. If scrubbing is needed, scrub with a baking soda solution, then hit it with the vinegar again. What’s hard about that? And yet, nearly every comment here says “What do I do about this or that mold situation I have?” Uh, covered in the dang article! Or “Well, I just hit it with bleach!” Uh, covered in the dang article, including the title! Why bother even commenting under an article you all are refusing to read?!?!

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