Why Your Washing Machine Might Be Making You Sick (Especially if You Have a History of CIRS)

When it comes to a water-damaged building, individuals who develop Chronic Inflammatory Response Syndrome (CIRS) may become ill not only from fungi, but also from bacteria and the byproducts these organisms release—either from themselves or from the materials they are breaking down.

Recently, my husband and I had the opportunity to purchase a new-to-us property here in coastal Georgia. As is often the case, we discovered some prior water intrusion issues that had not been properly addressed. After completing targeted remediation of the affected areas, I felt comfortable in the home overall. However, I noticed something very specific: when I spent even a few minutes in the laundry room, I would begin to feel slightly lightheaded and dizzy.

This caught my attention.

The home came with a front-load washer, which I had never owned before. I have always preferred top-load machines—with or without an agitator—as I find they clean more effectively. That said, my initial concern was not performance—it was how I felt in that room.

Microbial grownth inside the big fold of a frontload washer.

Microbial grownth visible near the light of afrontload washer.

View of the back and big fold of the washer's rubber boot after removal. This cannot be cleaned

For patients who have gone through treatment for CIRS and reached remission, there is often a heightened awareness of re-exposure. Ritchie Shoemaker describes this phenomenon as “getting sicker quicker.” That is exactly what I was experiencing.

The Problem with Front-Load Washers

While multiple surfaces within a washing machine can harbor microbial growth, the most significant area of concern is the rubber gasket at the door—commonly referred to as the “boot.”1 This boot is typically made of a synthetic material such as ethylene propylene diene monomer (EPDM) rubber. In theory, synthetic materials are not ideal food sources for microbes. However, when these materials remain wet for prolonged periods and accumulate debris—detergent residue, lint, dirt—they become an excellent environment for microbial growth.

Front-load washers are particularly prone to this issue because the design traps moisture within the folds of the gasket. Most boots have at least two folds—a shallow outer fold and a deeper inner fold—both of which can retain water.

When I opened the washer at our new-to-us place, I immediately noticed a musty odor. On closer inspection, there was visible buildup—what I would describe clinically as a combination of bacterial growth, fungal elements, and biofilm formation.

At that point, the source of my symptoms was clear.

Cleaning vs. Replacement

I initially attempted to clean the gasket, but it was not salvageable. I scheduled a boot replacement, although, in hindsight, the better decision would have been to replace the entire machine.

I spoke with my appliance repair professional, who confirmed what many in the industry already know: all washing machines develop some degree of internal contamination over time, but front-load washers are significantly worse. He does not recommend them, particularly in humid climates like ours in coastal Georgia, where moisture persists year-round.

He also noted—interestingly—that they are more difficult to repair and, in his opinion, do not clean as effectively as top-load machines.

What the Research Shows

Out of curiosity, I looked into the available data. In the CIRS world, we understand that microbial growth timelines are relatively short:

• Bacteria can begin forming within 2 hours of moisture exposure

• Fungi can begin colonizing within 48 hours

  
  

When it comes to washing machines, most research comes from the detergent and appliance industries. Unfortunately, these studies tend to focus on human pathogens rather than the broader spectrum of organisms associated with water-damaged environments. Still, it is clear that bacteria, fungi, and biofilms do develop, take hold, and persist. Biofilms recovered from washing machines have been shown to contain up to 94 different microorganisms, with approximately one-third classified as potential human pathogens.2 These include organisms such as:

• Klebsiella pneumoniae

• Pseudomonas aeruginosa

• Serratia marcescens

• Citrobacter freundii

Interestingly, fungal burden in these studies was lower than bacterial burden and consisted largely of non-pathogenic species.3 However, this does not rule out the presence of environmentally derived fungi or microbial fragments relevant to CIRS, as these were not the focus of the studies.

Why This Matters

For most people (at least 76% of the population), a contaminated washing machine may not cause noticeable symptoms. For someone with a history of CIRS or a genetic predisposition to developing it—this type of exposure can be enough to trigger symptoms quickly.

And importantly, this exposure is often overlooked. We tend to think about obvious and expensive sources of contamination—leaks, visible mold, HVAC systems—but not appliances that we use daily.

Practical Takeaways

If you live in a humid environment or have a history of CIRS:

• Be cautious with front-load washers. Strongly consider avoiding them altogether.

• Regularly inspect and clean the door boot

• Wipe the boot clean and dry after every wash

• Leave the door open between uses to allow drying

• Consider periodic high-heat cleaning cycles

• If you detect a musty odor, investigate further

In most cases, the most effective solution may simply be the replacement of the unit with a top-load model. This may also be a simple, relatively low-cost measure that can improve mold testing in a home.

This was a good reminder—even for me—that sources of exposure are not always obvious. Sometimes, they are hiding in plain sight, in something as routine as doing laundry.

Sources:

1. Osta-Ustarroz P, Theobald AJ, Whitehead KA. Microbial Colonization, Biofilm Formation, and Malodour of Washing Machine Surfaces and Fabrics and the Evolution of Detergents in Response to Consumer Demands and Environmental Concerns. Antibiotics (Basel). 2024 Dec 18;13(12):1227. doi: 10.3390/antibiotics13121227. Erratum in: Antibiotics (Basel). 2025 Mar 11;14(3):292. doi: 10.3390/antibiotics14030292. PMID: 39766616; PMCID: PMC11672837.

2. Gattlen J., Amberg C., Zinn M., Mauclaire L. Biofilms isolated from washing machines from three continents and their tolerance to a standard detergent. Biofouling. 2010;26:873–882. doi: 10.1080/08927014.2010.524297.

3. Whitehead K.A., Deisenroth T., Preuss A., Liauw C.M., Verran J. Lateral force re-moval of fungal spores to demonstrate how surface properties affect fungal spore retention. Philos. Trans. R. Soc. A Math. Phys. Eng. Sci. 2022;380:20210344. doi: 10.1098/rsta.2021.0344.