Why Does My Washing Machine Smell?

The laundry room smells. Can’t place it at first — then you realize it’s coming from the washing machine itself. If you’re asking why does my washing machine smell, buildup is almost always the answer. Bacteria, mold, leftover detergent, a drain problem that’s been developing quietly — one of those is behind it. 

“Smelly washer calls are usually a gasket or a blocked filter. Ten-minute fix. People spend weeks running cleaning cycles on the drum and never touch the thing that’s actually causing it. “

— Mykola Beschasnyi, CEO, Fuse Monterey. 

Front-loaders are the worst offenders. A 2023 Consumer Reports survey of over 74,000 members found 13% of front-load owners reported mold or mildew — versus 3% of HE top-loaders. And a 2024 PMC study found that biofilms inside washing machines contain up to 94 different microorganisms, about a third of which are potential human pathogens. That’s what’s causing the smell.

How to Identify the Smell (and What It Means)

The type of smell narrows the cause fast. There are four main ones.

Smells Like Rotten Eggs or Sulfur

Sulfur bacteria reacting with minerals in your water — or stagnant water sitting in the drain hose. Sometimes a plumbing issue further down the line.

Smells Like Sewage or Drain

Almost always a drain issue. Clogged pipe, dry P-trap, buildup in the hose — sewer gas finds its way back through. Washing machine smells like sewage after a cleaning cycle? The drum wasn’t the problem. Washing machine smells like sewage even on a machine that gets cleaned regularly — the drum isn’t the issue, the drain is. 

Smells Like Mold or Mildew

The most common complaint.Gasket folds, drum, detergent drawer — moisture collects in all three and just sits there. Washer smells like mildew? Door’s probably been closed between every load. Or the rubber seal hasn’t seen a cloth in a long time.

Smells Like Wet Dog or Musty

Detergent residue and dirt sitting inside the machine. Over time it builds into a biofilm — which is exactly what that smell is.

How to Clean a Smelly Washing Machine Step by Step

Cleaning a smelly washing machine takes less than an hour. Five spots, in this order:

Clean the Drum

Empty hot cycle with two cups of white vinegar, or a washing machine cleaner tablet. Hot water breaks down residue and kills the bacteria causing the smell. Still smells after the vinegar cycle? Baking soda on the next one. Two cleaning cycles and the smell is still there — stop running cycles and go look at the gasket and filter directly. That’s where it is. 

Scrub the Door Seal

Pull the rubber gasket back and look inside the folds. That’s where the mold is. Wipe it out with a cloth and mild cleaner. Every two weeks if the smell keeps returning.

Clean the Detergent Drawer

Take it out completely. Rinse under hot water. Use a toothbrush on the corners where softener residue collects and quietly rots.

Check and Clean the Filter

Most front-loaders have a drain filter behind a small panel near the base. Clogged filters hold stagnant water — that’s why washer smells like mildew even after everything else has been cleaned.

Wipe Down the Exterior

Door edges, control panel, the rubber around the opening. Moisture collects here too.

How Often Should You Clean Your Washing Machine?

Once a month is the standard. Cold-water households need to clean more often — cold cycles don’t kill bacteria the way hot ones do. Heavy use, pets, or a lot of synthetic fabrics push the schedule closer to every two to three weeks.

Can Too Much Detergent Cause the Smell?

It can and it does. Excess detergent doesn’t rinse out cleanly — it coats the drum and the hoses in a sticky film that traps dirt and feeds bacteria. My washer smells worse lately and nothing has changed — more often than not, someone started measuring detergent less carefully.

HE machines need HE detergent in the right amount. More soap isn’t cleaner. It’s more residue. That’s the most common pattern we see when a washing machine smells bad and nothing obvious has changed — someone stopped measuring. 

Why Does My Washer Still Smell After Cleaning?

Because the problem is somewhere that wasn’t cleaned. Common missed spots:

• Inside the drain hose
• The housing behind the detergent drawer
• The P-trap connection at the wall
• Between the inner drum and the outer tub

If mold has spread into internal components, a single cleaning cycle won’t reach it. That’s when professional cleaning or a component inspection makes more sense than another round of vinegar.

How to Prevent Washing Machine Smells Long-Term

Two minutes after every load:

• Leave the door open — moisture needs air to leave
• Wipe the gasket dry — front-loader owners especially
• Measure the detergent — don’t eyeball it
• Run a hot cycle weekly even if most loads are cold
• Clean the filter monthly

That routine does more than any product marketed for cleaning a smelly washing machine. Knowing how to clean a washing machine that smells is one thing — building habits that stop it from smelling again is the other. Most cases where a washing machine smells bad repeatedly come down to skipping one of these steps consistently.

Top-Load vs. Front-Load: Which Smells More and Why?

Front-loaders, and it’s not close. The same airtight seal that cuts water usage traps moisture inside after every cycle. The rubber gasket folds collect water and debris. The horizontal drum holds more residue than a top-loader ever would. 

Ken Rudolph, senior director of product management for clothes care at GE, said it plainly in a Consumer Reports interview: residual moisture after the wash cycle is the biggest contributor to odor-causing bacteria in front-loaders. The gasket seals it in — unlike a top-loader where the opening stays exposed to air.

Consumer Reports data backs it up: 14% of front-load washer owners reported odor problems, compared to 6% of HE top-loaders and 3% of top-load agitators.

When to Call a Professional

Washing machine smells like sewer after everything’s been cleaned — stop cleaning and call a plumber. The drum isn’t the source. The drain line, P-trap, or vent stack is, and none of that responds to vinegar. 

Other reasons to stop DIYing and call someone:

• Mold has spread into internal drum components
• The drain hose is damaged or holds standing water
• The gasket is cracked or torn
• Smell came on suddenly alongside drainage problems

Fuse Monterey handles appliance diagnostics and repairs across the Monterey Peninsula. For front-load washer issues specifically, see our guide on front load washing machine maintenance. If the smell is coming from the drain connection rather than the machine, that ties into plumbing — similar issues show up in dishwasher leaks for the same reasons.

Frequently Asked Questions

What causes a washing machine to smell bad?

Mold and bacteria are the short answer. The longer one: trapped moisture that never fully dries, detergent residue that builds up into a biofilm, and drainage issues that let sewer gases back in. A 2024 PMC study found washing machine biofilms contain up to 94 microorganisms — roughly a third of them potential human pathogens. That’s the biology behind the smell. 

How do I get rid of the smell fast?

Hot cycle with vinegar, then scrub the gasket, clean the drawer, check the filter. That handles most cases of washing machine smells bad in one session.

Should I be concerned if my washer smells like rotten eggs?

Sulfur bacteria in the water supply is the usual suspect — often harmless. But if it doesn’t go away after a cleaning cycle, the drain connection or water line is worth looking at. Don’t keep cleaning the drum if the source is somewhere else.

Why does my washing machine smell like sewage specifically?

Drain problem. A blocked pipe, a P-trap that dried out, sewer gas pushing back through the hose. Washing machine smells like sewage and you cleaned the drum — wrong spot. If washing machine smells like sewer comes back after a full clean, a plumber finds it faster than another cleaning cycle will. 

What’s the best product to clean a smelly washer?

White vinegar and baking soda work. Commercial cleaners like Affresh or OxiClean go deeper. But the product matters less than covering all the right spots. How to clean a washing machine that smells means starting with the gasket and filter — not just running a cleaning cycle and calling it done.