You probably think your washing machine is the cleanest thing in your house. It literally spends its whole life filled with soap and hot water, right? Wrong. Honestly, it’s often one of the germiest spots in the modern home. Think about it—you’re tossing in sweaty gym gear, kitchen towels covered in raw chicken juice, and socks that have seen better days. All that grime has to go somewhere. While most of it flushes away, a nasty cocktail of detergent residue, fabric softener, and hard water minerals starts building up in the nooks and crannies you can't see.
If your "clean" laundry has a faint whiff of a damp basement, you've got a biofilm problem. Knowing how to clean washing machine inside isn't just about aesthetics; it's about stopping bacteria like Pseudomonas aeruginosa or Klebsiella pneumoniae from setting up shop in your drum. These aren't just scary-sounding names. They are real pathogens that researchers, like those in a 2019 study published in Applied and Environmental Microbiology, found thriving in residential machines.
The Gunk You Can’t See (But Can Definitely Smell)
Front-loaders are the worst offenders. It’s the door seal. That gray rubber gasket is basically a five-star hotel for mold. It stays damp, it’s dark, and it traps hair and lint. Top-loaders aren't off the hook, though. They hide their filth under the agitator or in the outer tub where you can't reach without a screwdriver.
Most people use too much detergent. It's a fact. Modern HE (High-Efficiency) machines use very little water, so if you're pouring in soap like it’s 1995, it won't all rinse away. That leftover soap turns into "scrud"—a charming industry term for the waxy buildup that coats the outer drum. Scrud is the primary food source for mold.
How to clean washing machine inside without breaking it
Don't just dump a gallon of bleach in and hope for the best. You need a strategy. First, check your manual. Some manufacturers, like LG or Samsung, have specific "Tub Clean" cycles that are calibrated to hit specific temperatures or use higher water levels. If you have that, use it.
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The Vinegar and Baking Soda Myth
Everyone loves a natural cleaning hack. You’ve seen the TikToks where people mix vinegar and baking soda and it fizzes up like a science fair volcano. It looks cool. But for cleaning a washing machine? It's kinda useless if you mix them together.
The chemistry is simple: vinegar is an acid (acetic acid) and baking soda is a base (sodium bicarbonate). When you mix them, they neutralize each other, leaving you with salty water and carbon dioxide gas. To actually get results, you have to use them in separate stages.
- The Acid Phase: Run a hot cycle with two cups of white vinegar. The acid breaks down the calcium and lime scale buildup from hard water. It also starts to eat away at the soap scum.
- The Scrub Phase: After the vinegar cycle, sprinkle half a cup of baking soda directly into the drum and run another hot cycle. The baking soda acts as a mild abrasive and deodorizer to finish the job.
When to Bring Out the Heavy Hitters (Bleach vs. Oxygen Bleach)
If your machine smells like a literal swamp, vinegar won't cut it. You need a disinfectant. Sodium hypochlorite—standard liquid bleach—is the gold standard for killing mold spores. However, never, ever mix bleach with vinegar. That creates chlorine gas, which is toxic. If you used vinegar recently, rinse the machine thoroughly before even thinking about bleach.
An alternative is sodium percarbonate, often sold as "OxiClean" or "oxygen bleach." It’s better for the environment and safer for the machine's rubber parts over the long term. Many appliance repair technicians, like the popular "Sabbath Appliance" experts on YouTube, suggest that oxygen bleach is actually more effective at breaking down the organic proteins found in "scrud" than liquid chlorine bleach is.
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Addressing the Biofilm in Front-Loaders
The gasket is the frontline. Pull back the rubber folds. You’ll probably find a slimy, black sludge. Use a microfiber cloth soaked in a 1:10 bleach-to-water solution and wipe it down. Don't forget the drain holes at the bottom of the seal; they get clogged with lint, which prevents the water from draining, leading to—you guessed it—more mold.
Check the filter. Yes, your washing machine has a filter. It’s usually behind a tiny door at the bottom front of the machine. Prepare for a mess. When you unscrew that cap, a cup or two of stagnant, smelly water will pour out. This filter catches coins, hair ties, and clumps of wet lint. If it's clogged, your machine can't drain properly, and you're essentially washing your clothes in recycled "dirty" water.
Dealing with the Top-Loader Agitator
Top-loaders feel easier, but they have a secret. If you have a center agitator, the top cap usually pops off. Inside, you might find a "fabric softener dispenser" that looks like a horror movie set. Pull it out and soak it in hot, soapy water.
For the deep clean:
Fill the tub with the hottest water setting. Add a quart of bleach. Let it sit for an hour. Agitate for a minute, then let it sit for another hour. This "soak time" is the secret to how to clean washing machine inside effectively. You have to give the chemicals time to permeate the layers of buildup on the outer tub.
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Why Your Detergent Choice Matters
Stop using liquid fabric softener. Seriously. It is essentially liquid wax. It coats the fibers of your clothes to make them feel soft, but it also coats the inside of your machine. This creates a waterproof layer that traps bacteria underneath it. Use white vinegar in the softener dispenser instead. It softens the water and helps rinse away soap without leaving a greasy residue behind.
Switch to powder detergent if you can. Many appliance repair pros argue that powder is more abrasive (in a good way) and contains bleaching agents that keep the drum cleaner than liquid detergents do.
Actionable Steps for a Fresh Machine
Maintaining a clean machine is easier than doing a "deep recovery" clean every six months. If you follow these steps, you won't have to deal with the "stinky towel" syndrome ever again.
- The Golden Rule: Always leave the door or lid open after a wash. If the inside can’t dry, mold will grow. Period.
- Wipe the Seal: After your last load of the day, take five seconds to wipe the moisture off the rubber gasket and the inside of the glass door.
- High-Temp Wash: Once a week, run a load of whites or towels on the "Sanitize" or "Extra Hot" setting. The heat helps kill off any developing biofilm before it becomes a problem.
- Monthly Maintenance: Run a dedicated cleaning cycle once a month using a specialized cleaner like Affresh or a simple dose of oxygen bleach.
- Dosage Control: Use half the amount of detergent you think you need. If you see suds during the rinse cycle, you’re using too much.
Start by cleaning the drain filter today. Most people haven't touched it since they bought the machine, and it’s likely the source of that mystery odor. Once the debris is cleared, run a high-heat cycle with a dedicated descaler to strip away the hidden mineral deposits. Keeping the mechanical parts clear of buildup doesn't just make your clothes smell better—it prevents the motor from overworking and extends the life of your appliance by years.