Bathroom Mold: Causes, Prevention, and Removal

Updated by Lisa A on January 21, 2019 in

Mold Remediation, Mold Testing, Mold Inspections

The bathroom is probably the first place we think about when we consider household mold. It's often found on grout in between tiles, on caulk that lines the bathtub and sink, on the shower curtain, even on the ceiling and walls—anywhere that's been exposed to excessive moisture or humidity for an extended period of time. 

Bathroom Mold


What causes mold in the bathroom?

Because mold thrives in a warm and humid environment with limited air flow, bathrooms are the perfect breeding ground for this fungus. Showers, especially warm and/or lengthy ones, probably contribute more frequently to bathroom mold issues than any other single activity. The grout in between shower tiles is especially susceptible, as this area is often pounded by water, and grout itself is porous, so water can seep in and sit, potentially cultivating mold.  Another frequent contributor to bathroom mold is the slow drip of a leaky pipe that has gone unnoticed.

A water intrusion event that has not been completely dried, such as an overflowed toilet or bathtub, could also result in a mold infestation. For example, if the large volume of water was not removed quickly enough, or if the job was considered "done" before the moisture content of the materials and the humidity level reached acceptable levels; under these circumstances mold can easily take root, which is why timely and thorough water mitigation is necessary after water intrusion.


How do I prevent mold in the bathroom?

To prevent mold from taking hold in your bathroom, humidity must be kept in check and any areas where water regularly pools must be dried completely, such as the floor just outside the bathtub or shower, the area behind the sink faucet, etc. Additionally, grout should be sealed, and caulk should be replaced when it shows signs of deterioration. 

It's a good idea after each use to rinse out the shower (to remove any soaps or oils) and then use a towel or squeegee to remove excess water from the shower walls. There are commercial products available, such as Tilex, that can be applied daily to thwart the growth of mold and mildew, and a vinegar/water solution can be applied as a natural alternative, though you'd want to rinse it off after a period of time so the smell does not linger. 

Every bathroom should have an exhaust fan, and this should be run during each shower and for about a half-hour afterward (depending on how many cubic feet per minute your fan can move) until all moisture has been exhausted from the room. An open window can serve a similar function, though not as effectively or quickly, and not in every climate.

Additionally, any leaks or flooding should be promptly addressed and the area thoroughly dried, using a dehumidifier and fans if necessary. The longer water sits in a particular area, the more likely mold is to take hold. 


How do I remove mold in the bathroom?

There are a lot of DIY methods for mold removal that homeowners can try, especially if the area in question is limited in scope and material affected. These include the use of vinegar, baking soda, hydrogen peroxide, Borax, and other common household products. (Bleach is not recommended, as it does not penetrate porous surfaces and so cannot kill the root system.) Home improvement stores also stock a variety of mold removers. It's important to remember, however, that any DIY attempts at mold removal should be accompanied by an appropriate amount of research on how to effectively and safely complete the task. Proper precautions must be taken to ensure that adjacent areas aren't contaminated in the process and that spores are not inhaled. If there is any question as to whether the type of mold involved is of the toxic variety, a mold testing professional can be hired and a sample sent to an accredited lab.

There are several circumstances under which you'd want to consider professional mold remediation, including if the area affected is large and involves different types of material, if the mold species is toxic, if you or anyone in your family is sensitive or allergic to mold, or after a water intrusion event, especially if the water involved is blackwater

A properly trained mold remediation specialist will be equipped to gauge the extent of the mold problem and pinpoint its origin (if unknown), and will carry out removal according to established industry standards. He begins the process by donning PPE (personal protective equipment) and sealing off the area affected, placing it under negative pressure so as not to contaminate other areas of the home. Materials that are not salvageable (Sheetrock, carpet, etc.) would be demoed and placed into sealed plastic bags for proper disposal, again so as not to contaminate other areas of the home as they are transported outside. All surfaces in the affected area would be HEPA-vacuumed to remove mold spores. A fungicide should be applied, capable of penetrating porous surfaces and killing the root system. Finally, the surfaces should be HEPA-vacuumed once more to remove any remaining dead mold spores (as even dead mold spores are harmful and can cause an allergic reaction). 

As always, prevention is much easier and less costly than remediation, so best practice would be to keep in mind the conditions that contribute to infestations and do your best to avoid them.

Wanna learn more about mold testing, remediation, and inspection? Visit our mold services page.

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Thanks to our mold remediation specialist Zach C for lending his expertise to this article.


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