If your washing machine smells like sewage, it is usually caused by bacteria buildup, clogged drain lines, trapped water in the machine, or plumbing vent issues. The odor develops when moisture, detergent residue, and dirt create the perfect environment for bacteria to grow inside the drum, filter, or drain system.
Let’s break down exactly why this happens and how to fix it.
Common Reasons Your Washing Machine Smells Like Sewage
1. Bacteria and Mold Buildup Inside the Drum
Over time, detergent residue, fabric softener, lint, and dirt stick to the inside of the drum. In warm, damp conditions, bacteria multiply quickly and create a sewage-like odor.
Front-load washers are especially prone to this problem.
2. Clogged or Dirty Drain Hose
If the drain hose is partially blocked, dirty water can sit inside the hose instead of draining fully. Stagnant water begins to smell like sewage after a short time.
This is one of the most common causes.
3. Blocked Pump Filter
Many washing machines have a pump filter that traps lint, coins, and debris. If it is not cleaned regularly, trapped debris begins to rot and produce a foul smell.
4. Sewer Gas Coming From the Drain
If your home’s plumbing vent is blocked or the drain trap has dried out, sewer gases can travel back up through the washing machine drain.
This causes a strong sewage odor even if the washer itself is clean.
5. Using Too Much Detergent
Excess detergent leaves sticky buildup inside pipes and the drum. That buildup traps bacteria and creates bad smells over time.
Using more soap does not make clothes cleaner — it often makes the problem worse.
How to Fix a Washing Machine That Smells Like Sewage
Follow these steps in order.
Step 1: Run a Hot Cleaning Cycle
Run an empty cycle on the hottest water setting.
Add:
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2 cups of white vinegar OR
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A washing machine cleaner tablet
This kills bacteria and dissolves buildup inside the drum.
Step 2: Clean the Rubber Door Seal (Front Loaders)
Pull back the rubber gasket and check for:
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Black mold
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Sludge
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Trapped debris
Wipe it thoroughly with vinegar or diluted bleach.
Dry it completely afterward.
Step 3: Clean the Drain Pump Filter
Locate the filter (usually at the bottom front panel).
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Place a towel underneath.
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Open the panel.
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Remove debris inside.
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Rinse and reinstall.
This alone often removes the sewage smell.
Step 4: Inspect the Drain Hose
Make sure:
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It is not kinked.
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It is not inserted too far into the wall drain.
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It is not clogged.
If needed, disconnect and rinse it out.
Step 5: Check for Plumbing Issues
If the smell continues after cleaning:
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The drain trap may be dry.
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The plumbing vent may be blocked.
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There may be a sewer line issue.
In that case, a plumber may be required.
How to Prevent Washing Machine Odors
Prevention is simple.
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Leave the door open after every wash.
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Use the correct amount of detergent.
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Run a hot cleaning cycle once per month.
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Clean the filter every 1–2 months.
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Avoid leaving wet clothes inside overnight.
Small habits prevent major odor problems.
Frequently Asked Questions
Why does my washing machine smell worse after I run it?
Running the washer can stir up bacteria and debris inside the drain system, making the odor stronger temporarily.
Can mold in a washing machine make you sick?
In rare cases, mold spores may trigger allergies or respiratory irritation, especially in sensitive individuals.
Is bleach or vinegar better for cleaning a smelly washer?
Vinegar is safer for routine cleaning. Bleach is stronger and better for heavy mold buildup. Never mix them.
Why does my washing machine smell like rotten eggs?
A rotten egg smell usually indicates sulfur bacteria or sewer gas coming from the drain system.
Final Thoughts
A washing machine that smells like sewage is usually caused by bacteria, trapped water, or drain problems. Cleaning the drum, filter, and drain hose solves most cases quickly. Regular maintenance keeps odors from coming back.
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