The Science of Washing Machine Stink Explained

Why does your washing machine stink? Many people will tell you a simple answer but sometimes we like to get a little deeper. Hopefully this article will bring a little more scientific understanding into the causes of a smelly washer.

In an article published in 2013 for the Society of Applied Microbiology, a team of researchers set out to answer this question with a wide array of tests. To start, they needed to see how the age of a washing machine and stink level would change the results. So they procured four different front loader machines from different manufacturers to experiment on. Out of the four, they had one that was never used, one that was used but fairly new, and two that were stinking to high heaven. 

After they obtained their quartet of washers, they wanted to determine a number of different things: 

Which parts of a washing machine gets the stinkiest?

What kind of germs were living in the washers?

How does stink grow over time in a closed machine?

How does washer age and condition or maintenance affect smell?

What level of cross contamination could occur when washing clothes in a smelly washer?

They cover these questions more in depth in the article, which I would definitely recommend reading (You can find the link at the bottom). For those of you who want a quicker explanation without the science-speak, I’ll  give you a concise overview of what they found out about each of these questions. 

One question many people ask is “Where is that smell coming from in my machine?”  As the researchers investigated this question they found that a never before used washing machine had no smells in any of the detergent drawer, drum, sump, or seal; Whereas, a clean, but used machine had no smells in the detergent drawer, slight smells in the drum and around the seal, and a little more in the washer’s sump. Not too shabby! On the other hand, the two stinky washing machines had a medium stink in the detergent drawer and major stink in the drums, sumps, and seals. No kidding, right?

Turns out, these “stink lines” were closely related to germ growth. They found that a corresponding number of germs grew proportionately with the smell levels. In other words, the worse an area smelled the more germs were hidden there. In the two newer ones that didn’t smell as bad the researchers found 6 different kinds of germs compared to the 47 different kinds they found in the malodorous ones. 

All these germs contribute to odor. But how long does it take for a washing machine to start stinking and develop these types of germs? In a new washer, it took 24 hours before the researchers found any significant smells. Although, by 48 hours a slightly stinky smell began to fill the machine and even stick to the clothes. There’s nothing as discouraging as forgetting to switch the laundry around just to find that you have to rewash them new machine notwithstanding!

How stinky can older machines get? Although these washers were already foul, after 24 hours they nearly doubled in smell! That’s when you know your machine needs a cleaning. At 48 hours, they were topping the charts. Clearly the newness of a washing machine affects smell, but it’s not the only factor. Water can’t escape If laundry is left in the wash for too long or the door is closed after a load, and this causes the machine to stink. 

Furthermore, a stinky washing machine can lead to cross contamination as the researchers discovered. If you are washing clothes in a stinky washing machine you are very likely cross contaminating your clothes with whatever germs are living in your washer! It’s better to clean the washer ASAP rather than suffer with dirty, musty smelling clothes created by an unsanitary washer. Even new machines are subject to the stink monster. However, if a machine is well ventilated and cleaned regularly, bad smells can be avoided altogether. Using detergent helps too, as the researchers found traces of detergents and perfumes in the machines. However, it should be pointed out that they didn’t completely stop odor from occurring like you would suppose.  

In conclusion, it’s important to take the time to clean your washing machine specifically even if you’re good about switching loads or leaving the door open. We at Eco-Gals designed our washing machine cleaner, Eco-Swirlz, to be an easy and eco-friendly way to clean a washer. Routinely cleaning your washing machine once a month helps to maintain it and keep it clean. This habit combined with both switching the laundry around and leaving the door open will help air out your machine and prevent odors from collecting so you can feel confident that your clothes are actually being cleaned. 

Like I mentioned before, The article this post is based on goes into much more depth. Among other things they explain what tests they conducted, what materials they used, and how they ranked smells. The charts they used are very informative in showing what a washing machine’s relationship is with smell and sanitation. Definitely check it out at the link below!

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Article Cited: 

The potential impact of washing machines on laundry malodour generation