How to Get Rid of Mold on Grout

Michael Rubino

November 23

Mold on grout is one of the most common places that fungus among us pops up in our homes. In fact, chances are that it’s happened to most, if not all, of the population. That being said, just because it’s a common occurrence does not mean we should brush it off and allow it to continue. 

Any mold growth in a home can trigger adverse health reactions and increase the chances of another mold problem developing elsewhere. 

Knowing how to properly remove mold on grout and prevent it from occurring in the first place is a key detail in maintaining a healthy home. 

Here’s what you need to know. 

Why Is There Mold on Grout?

Prevention and remediation practices are built upon understanding why the mold is there in the first place and what happens when a colony develops.

Mold typically needs two components to begin growing: food and water.¹ If these are present for 24-48 hours, mold will begin growing roots called hyphae and colonize the surface. This is a key detail to remember because grout is porous, allowing the roots of a mold colony to reach deep within the surface. 

Once the colony is established, it will begin releasing microscopic particles called spores into the surrounding area.²’³ Some species of mold also release microscopic particles called mycotoxins, which are toxic to the human body.⁴ While these are regulated in our food products, they have yet to place a regulated limit on levels in our homes.⁵ 

Adding in the Grout Factor

mold on grout

Taking all of this into account, it’s pretty easy to see how mold in grout occurs. Grout is usually in moisture-rich rooms like the bathroom, kitchen, and laundry room, providing an abundance of moisture that the porous material can trap. Coupled with structural issues such as misaligned tiles and cracks, which can trap water, you’ve got a perfect water oasis. 

As for an edible source, particles from the air, water, household products, and more can create the ideal conditions for growth. If the grout isn’t cleaned often enough, these particles will build up and create an edible buffet for a mold colony. 

Before you know it, poof, you’re staring down at mold on grout. 

Is Mold on Grout Dangerous?

The common misconception is that since mold is all over the world, it’s not a big deal when it’s in our homes. That’s not true. 

When mold releases spores in nature, they’re able to disperse throughout the entire planet. However, mold in a home that’s continually shooting off spores like a confetti cannon at a music festival doesn’t have the world to go through. Instead, those particles have a much smaller indoor environment. 

With how homes are built nowadays to promote energy efficiency, there’s little airflow between inside air and outside air. That leads to all of the moldy particles remaining inside the building, floating around that indoor space, and landing on whatever surface they come into contact with. That’s why issues such as mold in grout are indoor air quality and contamination nightmares.

The Health Aspect

The key ability for indoor mold growth to impact our health is the size of the particles in question. They’re so small that they can be inhaled, ingested, and absorbed into the body.⁶

The EPA classifies these teeny-tiny specks as particulate matter and breaks them down into two categories, both of which are inhalable.⁷

microscopic particles
These two categories are:
  1. PM10: particles that have a diameter of around 10 micrometers or less.
  2. PM2.5: fine particles that have a diameter of around 2.5 micrometers or less.

Inhaling a few spores or mycotoxins throughout the day triggers the body to deploy the immune system to kick them to the curb ASAP. When you’re living in a house with a thriving colony, though, that’s a significantly higher number of particles to fight. 

Considering that the average person breathes 20,000 breaths a day and spends around 90% of their time indoors, that’s a serious task for the immune system. It will attempt to keep up with the onslaught, but it can eventually get bogged down and malfunction.⁸’⁹’¹⁰’¹¹’¹² This can lead to a variety of chronic symptoms and leaves the door wide open for other conditions to take hold, such as Aspergillosis, Chronic Fatigue Syndrome, and Mast Cell Activation Syndrome. 

Common symptoms of exposure include:
  • Headaches and migraines
  • Joint and muscle pain
  • Chronic fatigue
  • Brain fog
  • Hair loss
  • Hormone imbalances
  • Mood swings 
  • Anxiety and depression
  • Digestive issues
  • Cold/flu symptoms

How Do You Get Rid of Mold on Grout?

If you’re staring down at mold on grout, you need a solid action plan on how to get rid of it. That way, your home won’t be bombarded with an army of microscopic particles. 

First things first, do NOT use bleach.¹³ This harsh chemical does not make the cut when it comes to battling mold. While it may kill the surface mold, dead particles and the roots must also be dealt with.

Properly handling any remediation project means ticking off three boxes: 

  1. Remediate the sources properly, including handling the living colony, dead particles, and roots.
  2. Identify and address the problems that led to those sources in the first place.
  3. Eradicate all contamination created by those sources, including mycotoxins and bacteria.

Failure to accomplish any of the above can lead to mold coming right back or continued exposure to contaminants left behind. 

Grout is particularly difficult because it’s porous, meaning that the roots and microscopic particles can reach deep within the surface and be difficult to remove completely. 

With that in mind, here are the steps you should to get rid of mold on grout:
  • Put on your protective gear (masks and gloves)
  • Fill a spray bottle with hydrogen peroxide
  • Spray on the surface and let it sit for at least 10 minutes
  • Wipe away with a microfiber towel
  • Complete the process at least two more times, allowing the cleaning product to sit for 30 seconds, to ensure mycotoxins and bacteria are removed (use a clean side of the microfiber towel with each wipe down)
  • Throw the towel away and allow the space to dry completely
  • Deep clean the room using a HEPA vacuum, botanical cleaning products, and microfiber towel

If the mold comes right back immediately, that typically indicates a larger problem. You can attempt the cleaning process again, but it’s best to remove the grout, clean the surface, and apply a new layer. 

Keep an eye out while you’re regrouting, though. If you see that the wall behind the grout is wet or if mold is growing on the wall itself, that indicates a larger issue. Remember, in order to handle a contamination situation, the issue that led to the growth must be resolved and all contamination removed. If there’s mold growing into the wall, that has to go.

In this instance, best to call in the professionals. An inspector should come in and assess the situation to determine how big the contamination problem is and the issue that led to it in the first place. A remediation team can then use this data to come in and properly remove all of the contamination. 

The Mold Came Back… Again

mold growth

If you replace the grout but that mold pops right back up, it could indicate a much bigger contamination issue. The baseboard behind the surface could be wet, or there could be wonky tiles and/or improper grouting, leading to a permanently wet environment. Aka, a habitable home for mold.

In this scenario, it’s best to call in a qualified mold inspector and see what the issue is. The mold could be growing deep within the wall and needs to be removed, or a hidden mold problem could be elsewhere in the home. The more spores there are in the indoor environment, the higher the chances are that they’ll stumble on other habitable areas like your grout.

If you notice some structural issues, you can get started on resolving them, but a mold inspector is still a good idea just to make sure there’s no hidden mold. The faster you catch an issue, the sooner you can go about hiring a qualified remediation company to resolve it.

Should you have any questions or concerns during the process, reach out to an expert. They’ll give you their expert advice on how to go about handling the issue so that you can have peace of mind your home is once again a safe space.

How Do You Prevent Mold on Grout?

The best way to handle mold on grout is to prevent it from happening in the first place. Avoidance not only saves you time and money but also helps promote healthy living by maintaining safe indoor air quality and a clean living environment. One problem can easily turn into multiple mold factories throughout a home as the spores opportunistically find other habitable areas to colonize.

Here are some steps to take to prevent mold on grout.

Cleaning Often

preventing mold on grout

Cleaning removes rogue mold spores hanging around and gets rid of food sources like dust and other organic matter. But, once again, do not use bleach! For solid grout decontamination, spray it down with hydrogen peroxide. Let it sit for at least 10 minutes, and then wipe it with a microfiber towel.

Hydrogen peroxide can penetrate semi-porous surfaces and bring any particles (like mold spores) up to the surface, and microfiber towels are 100 times better at removing tiny particles than regular rags. Adding this to your cleaning regime can work wonders to prevent mold.

Staying on Top of Structural Integrity

As mentioned earlier, misaligned tiles and bad grouting jobs can lead to built-up moisture problems. Any gaps or holes can let in water and trap organic particles, creating ideal conditions for mold growth.

Preventatively fixing these issues when they pop up can help avoid mold on grout and larger contamination situations.

Replacing If Needed

Unfortunately, grout doesn’t last forever. Regularly check for cracked, missing, or crumbling grout throughout the home. If this pops up, go ahead and jump into replacement so that moisture doesn’t get the opportunity to build up and allow for mold growth.

Reducing Moisture

One of the best ways to prevent mold on grout (and in general) is to eliminate the components needed for growth. In this case, that makes moisture public enemy number one. 

Reducing moisture can include:

  • Creating airflow by turning on exhaust fans when using the room and cracking a door or window
  • Wiping up any spills immediately
  • Keeping windows and doors closed on rainy and/or humid days
  • Squeegeeing any wet surfaces after use
  • Investing in a dehumidifier
  • Maintaining indoor humidity levels between 30-50%¹⁴

This isn’t an exhaustive list, but tackling a few steps at a time can help ensure mold doesn’t get the chance to grow in your home.

You’ve Got This

clean indoor air quality

Dealing with mold can seem like a daunting task, but as long as you have the right information and tools, you’ll be prepared to handle any contamination situation that comes your way like mold on grout. Battling that fungus among us is simply a part of maintaining a healthy home. The less contamination that’s present, the healthier and happier your indoor space will be. 

While society may not talk about the impact our indoor spaces have on health, that doesn’t mean we should consider them in the wellness equation. They’re one of the greatest routes of exposure we have! Keeping them in tip-top shape will help ensure our bodies aren’t battling contaminants every time we step inside the building. No one wants to deal with that. 

Health begins at home.™


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