How bad is it really to never clean your washing machine?

There’s nothing quite like pulling a fresh load of laundry from the dryer – so clean, crisp and fragrant.

But what if we told you that your freshly laundered clothes and sheets were probably dirtier now than before the foam session? Unfortunately, that’s probably the case if you haven’t cleaned your washing machine in a while.

Yes, you have to wash your washing machine. Although it may seem crazy to clean your cleaning device, it is actually quite necessary.

Think of it like this: your washing machine deals with everyday dirty laundry (think: sweaty socks, dirty towels, and other unmentionables), so it can turn into a cradle of creepy critters. These pesky pathogens can thrive inside your machine and on your clothes, eventually finding their way to you. Uh.

But, despite the ick factor, can these germs actually make you sick?

Here we talked to Charles Gerba, PhD, a microbiologist at the University of Arizona, to see if a dirty washer can harm your health. Plus, get tips on how to clean your washing machine to maintain a germ-free environment.

Your washing machine is a humid environment, which means it’s a stellar setting for the breeding of disruptive microbes.

The most persistent pathogens are viruses like norovirus and adenovirus, Gerba says. But washing machines are also a breeding ground for bacteria such as salmonella, he says.

OK, we know what you’re thinking: doesn’t detergent kill those bad bugs?

Not always. For one thing, bacteria and viruses can survive a cold water wash, says Gerba.

Example: In an older but still relevant study from July 2007 in ​Applied and environmental biology​Gerba and colleagues noted that washing with detergent alone was ineffective in removing and inactivating enteric viruses such as adenovirus, rotavirus, and hepatitis A.

But the biggest problem is the sheer volume of viruses found in fecal-stained underwear. Yes, in the average pair of adult underwear, there’s about 0.1 grams of feces (for reference, that’s a quarter of a peanut by weight), Gerba says.

And significant concentrations of the virus — up to 100 billion per gram of feces — are present in the poop of infected people, Gerba says.

Even if you don’t see visible skid marks, these viruses can still linger in your drawers, he adds.

The problem is that germs that become infected in your feces can grow in your washing machine and contaminate clean clothes, including your next wash. And if you touch a contaminated object or surface (like clothing or the machine itself) and unintentionally put your dirty hands in your mouth, you can get infected.

“It depends on your immune system,” says Gerba. “Usually the elderly, the very young, and the immunocompromised are most at risk.”

Those most likely to get sick can likely develop diarrhea, the main symptom of norovirus, adenovirus and salmonella, Gerba says.

But these infections can cause a wide range of illnesses, from mild to severe.

According to the CDC, possible symptoms of norovirus include:

• Diarrhea
• Vomiting
• Nausea
• stomach pain
• Fever
• Headache
• Aches

Speak CDCpossible symptoms of adenovirus include:

• Acute gastroenteritis (inflammation of the stomach or intestines causing diarrhea, vomiting, nausea and stomach pain)
• Cold or flu symptoms
• Fever
• Sore throat
• Acute bronchitis (inflammation of the airways)
• Pneumonia
• pink eye
• Inflammation or infection of the bladder
• Neurological disease (conditions that affect the brain and spinal cord)

Speak CDCSalmonella symptoms can include:

• Diarrhea (which may be bloody)
• Fever
• stomach cramps
• Nausea
• Vomiting
• Headache

Again, it depends on who you live with and their level of risk. Typically, “I would do it once a month for odor control if no one is sick in the household,” Gerba says.

But if you have young children (under 5), Gerba advises you to rinse your machine more often. This is because children’s clothes, especially their underwear, tend to have more poop particles (read: more potentially infectious agents).

In that case, clean your machine after you’ve done your child’s laundry, says Gerba. About once a week should be enough.

Here are Gerba’s tips for cleaning your washing machine and keeping it germ-free:

• First, wipe down the inside of the machine and the seals around the door with an all-purpose cleaner, then clean the filters and drain. It’s important to get rid of this grime, as the debris can accumulate and create an even more attractive atmosphere for opportunistic microorganisms.
• To sanitize, run an empty load through hot water and bleach or a bleach substitute. Temperature plays a central role in pathogen control: to properly inactivate enteric viruses and bacteria, your water temperature must exceed 40 to 60 degrees Celsius (i.e. 104 to 140 degrees Fahrenheit), according to a June 2021 mini-review (co-authored by Gerba) in ​Applied and environmental microbiology​.

Here are his other suggestions for ensuring sanitary laundry:

• If you sort clothes on a table or counter, always sanitize the area after each use.
• Wash your hands or use hand sanitizer after sorting dirty laundry and/or putting washed wet clothes in the dryer.
• If you wash clothes in cold water, use bleach whenever possible, which can significantly reduce bacteria and virus counts, according to the June 2021 article in ​Applied and environmental microbiology.​
• Always wash your underwear and diapers separately (and on your last load of the day) with bleach or a bleach substitute.
• Dry your clothes on a high heat to drastically reduce microbial levels, according to the June 2021 article in ​Applied and environmental microbiology.Longer drying can also help.

Poop-polluted panties aside, slacking off on cleaning your machine probably isn’t too bad as long as you’re in good general health.

Still, you should get into the habit of keeping a washer hygienic (a foul smell is a telltale sign that your machine needs scrubbing). Again, a monthly disinfection schedule should be enough to control unpleasant odors and keep your device running smoothly.

But for people who are more likely to develop serious illness – young children, immunocompromised people and the elderly – keeping a machine germ-free can be a smart strategy to reduce the risk of infection.