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4 Natural Ways to Kill Black Mold

There’s nothing like returning to your beautiful Boston home after the House Bliss Cleaning team has been in to professionally clean your house. You instantly feel calmer to see your clean home, and you plan soaking up in the bathtub and jump in the shower to wash away your daily stresses in your gleaming shower. But, you look down and spot those familiar black stains still swarming around in the grout and underneath the enclosed door silicone. 


“Ugh! The cleaners didn’t clean this off like they were meant to!”

It seems so simple to you, all the cleaner needed to do was to soak the mold in bleach and scrub it clean until it was all gone. “So why didn’t they complete this basic cleaning task?” – You wonder.  

In this article, we aim to explain why it’s not that simple to eliminate mold from your home, why bleach sometimes is not the solution, why we use strongly recommend an eco-friendly approach instead to kill mold and what you can do to evict these bad boys from your home completely. 

A title wall with mold growing in the grout
Grout mold

DISCLAIMER: I am not by no means a mold expert or a biologist with a speciality in studying mold. I am just a mere house cleaner with a special interest in this stuff so I can get rid of it and advise my clients to the best of my ability. Thanks to the wonders of the internet, I did some research that helps me understand what mold is and the best ways to tackle it. 

What is Mold?

Mold is a fungi and like all bacteria, it has its good guys and bad guys. The good guys tend to stay outdoors acting as nature’s cleaner, decomposing and recycling nutrients from dead plants and animals. However, these good deeds are often shadowed by the actions of their rebellious brothers, who target and attack our homes. 

All types of mold thrive in environments that are damp or wet, making places like your shower and bathroom the perfect habitat for them to breed. Other common sources of excessive indoor moisture that can lead to moldy problems in your home can be caused by roof leaks, flooding, rain getting through cracked window frames, damp basements and condensation on cold surfaces.


If small growths of mold are detected early enough, it’s typically not a health concern. However, if it’s not treated properly and allowed to multiply, then we have a problem. Most people don’t react to mold exposure. 

The US Center for Disease Control and Prevention (CDC) states that living in a building with mold damage for a long time can cause respiratory disease, allergic reactions, and fungal infections. 

Different Mold, Different Results


Pink mold is an imposter. It doesn’t fit into the mold gang and is more of a bacterial colony of Serratia marcescens. However, there is a shared love for moist environments and it loves to feed on soap scum and fatty deposits in soap and shampoo residue. 

Pink mold is pretty harmless for most people and its vibrant coloring can make it easy to spot. With the right products and some elbow grease, pink mold easily falls victim to regular cleaning services from the House Bliss team.

We also take necessary precautions to prevent pink mold forming and it’s pretty easy for us to remove when we see it forming. Help us out by keeping the room well ventilated, dry and clean to prevent pink mold from returning. 

Now, let’s talk about the big guys:


When anyone spots black mold growing in their home, they immediately assume that it is the black mold: Stachybotrys chartarum. This type of mold is highly toxic and can produce mycotoxins, which are harmful when inhaled or ingested. But unless it’s a large amount of mold spread out over something that is severely water damaged, it’s likely to be more of a generic bathroom mold. This, you can clean yourself or call us in to tackle it. 

However, this isn’t to say that black mold is easy to wipe out. We’re confident that black mold will be gone from non-porous materials like metal, glass, tile, bathtubs, sinks, countertops, guaranteed with our deep cleaning. 

Unfortunately, we have received complaints from clients who expected our crew to wipe out mold that has grown in porous materials, like wood, wall, and grout it requires to be done by a trained Mold Removal Specialist who is equipped to contain and kill the mold from its source. For instance, mold growth on wood may need to be sanded, and if mold is growing on tile grout or silicone sealer, most likely it’s deep under the title. So these types of mold problems are a repair issue, not a cleaning issue.  

Keep in mind that the EPA (Environmental Protection Agency) suggests that if an area is larger than 10 feet by 10 feet should be handled by a professional mold removal.

Mold growth on hardwood floor outside of shower

Why We Can't Promise to Kill Mold Even Using Bleach?

TRUE STORY: A dear client of ours from Brookline contacted me and asked why the cleaning team did not tackle the ‘black stuff’ that was growing on the wooden floor next to the enclosed shower in her master bath. 

“Maybe try using bleach or something?” 

TRUTH: Bleach can kill every species of indoor mold.

Yes, chlorine bleach can kill mold and leaves a surface sanitized and resistant to future mold growth. But, before you get up and run towards that big bottle of bleach you have in your laundry room, you need to know that it is only effective if the mold is growing on non-porous materials such as tiles, glass, and countertops. 

Another disadvantage of using bleach is that it inhabits harsh, toxic chemicals, which can do more damage to your health than the mold can! So it is not recommended as a routine practice for cleaning. In addition, bleach causes damage to marble and natural stone floors and we would not want to be responsible for that.  

Ultimately, bleach does not kill mold that is growing on porous materials such as wood and drywall. It will kill the mold you can see on the surface and it will trick you into thinking you have solved the issue, but it will only be a matter of time when the dormant roots within the material, that cannot be killed with bleach, will return. 

We love to share tips for preventing mold and natural mold cleaning solutions that we’ve learned since we started our company, such as a solution of borax and tea tree oil that I made for my client in Brookline, as as an alternative and advise her to keep the area well ventilated. 

There are safer, alternative methods for killing mold that is not only MORE effective than bleach but also less harmful. These are some of our favorite natural mold-killing products:

Our Favorite Mold Prevention Methods


Borax is a product we depend on again and again for stubborn bacteria and deep cleaning. For starters, it is a natural cleaning product and is only toxic if you’re silly enough to drink it. It doesn’t emit dangerous toxic chemicals and has a pH level of about 9, making it low toxicity. Borax is budget-friendly and when mixed with water, makes a great mold-killing solution:

  • Create the solution using a ratio of 1 cup of borax per gallon of water
  • Dip a scrubbing brush into the solution to scrub the mold off the surface
  • Wipe the surface with a microfiber cloth to prevent particles floating in the air
  • No need to rinse as Borax also prevents mold from returning
Box of Borax


Another natural product, vinegar is a mild acid that can kill 82% of mold species and is non-toxic. Use white distilled vinegar for the best results:

  • Pour vinegar into a spray bottle. No water needed.
  • Spray the vinegar onto the moldy surface and leave it to work its magic.
  • Wipe the surface with water and a microfiber cloth, and allow to dry.

Vinegar can also be used as a preventative measure to keep mold away. Simply spray it onto surfaces that are prone to mold attacks. If you’re worried about the smell, add in some drops of essential oil into the solution to make it more easy on the nose. 

Glass bottles filled with vinegar and red apples near them


Baking soda is natural, non-toxic, cheap, deodorizes your home AND absorbs moisture. It can also be mixed with vinegar for an extra punch of mold-killing action.  It’s the ultimate, perfect solution! 

  • Add one-quarter of a tablespoon of baking soda to water in a spray bottle
  • Shake and spray the solution onto the infected area
  • Use a sponge or scrubbing brush to remove the mold Spray the area again and let it naturally dry
  • Spray the area again and let it naturally dry
a jar with baking soda and a wooden scoop


Tea tree oil is probably the most effective natural killing solution out there, but also the most expensive. It’s completely harmless, pleasant on the senses and is antibacterial:

  • Add tea tree oil to water in a spray bottle at the ratio of 1 teaspoon per cup of water
  • Spray the solution onto the infected surface
  • Leave to kill and dry naturally

At House Bliss Cleaning, we deal with mold growth that is less than 3 square feet every day and use natural daily shower cleaners or our own solution of water, soap, vinegar, tea tree, and red thyme to eliminate mold from bathrooms.  


Bathroom mold is our thing. So if you are seeing mold on walls, under carpets, under the sink or in any other areas around your house besides the bathroom, it’s time to call in a professional that is experienced in mold evaluation and remediation. This is also recommended for any mold growths that are larger than 10 square feet.

If you have mold growths in your home and you want the problem sorted quickly and efficiently, learn how we can help you eliminate mold with a deep cleaning service and prevent it from returning by carrying out reoccurring cleaning services

Your home is your haven.  

How about you? Do you have any experiences with anything in your bathroom that your housecleaner doesn’t seem to be able to clean well? Explain in the comments below. 

A small brown bottle with essential oil and a green Melaleuca branch

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