The most common cause: a blocked drain or vent pipe
A sewer smell from your dishwasher usually means water is sitting in the machine instead of draining out, or the drain line is backed up. When water sits, bacteria grow and produce that rotten-egg or sewage odor. The blockage can be in the dishwasher's own drain pump, in the hose that runs to your sink, or in your home's main drain line.
The second most common cause is a clogged or kinked drain hose. If the hose that carries water from the dishwasher to the sink drain gets pinched, twisted, or filled with food debris, water backs up into the machine. Check under your sink to see if the hose is bent sharply or if water is pooling around it.
Key Takeaways
- A sewer smell almost always means water is not draining properly from the dishwasher, allowing bacteria to grow.
- Check the drain hose under your sink first — it may be kinked, clogged, or disconnected from the sink drain.
- The dishwasher's filter and spray arms can trap food debris that rots and smells; cleaning these takes five minutes and costs nothing.
- If the smell persists after cleaning the filter and hose, the problem is likely in your home's main drain line and may need a plumber.
How to clean the filter and spray arms
Start here because it is the fastest fix and costs nothing. Open the dishwasher door and look at the bottom. You will see a cylindrical filter (usually plastic, sometimes stainless steel) that sits in a well. Twist it counterclockwise to remove it. Rinse it under hot running water and use an old toothbrush to scrub away any food, grease, or buildup. If the filter is very dirty or smells, soak it in hot water with a tablespoon of baking soda for 15 minutes, then scrub again.
While the filter is out, look into the well where it sat. Use a damp cloth or paper towel to wipe out any debris, slime, or buildup. Then locate the spray arms — there is usually one at the bottom and one under the top rack. These are the rotating arms that spray water during the wash cycle. Check the small holes in each arm for food particles or mineral deposits. Use a toothpick or small wire to poke through any blocked holes. Rinse the arms under hot water, then reinstall the filter by twisting it clockwise until it is snug.
Run the dishwasher empty on a hot cycle to rinse everything out. If the smell is gone, the problem was trapped food debris. If it remains, move to the next step.
Check and clear the drain hose
Turn off the dishwasher and open the cabinet under your sink. Locate the drain hose — it is usually a ribbed plastic tube running from the dishwasher to either the sink drain or the garbage disposal. Look for kinks, twists, or sharp bends. The hose should have a gentle curve, not a tight fold. If it is kinked, carefully straighten it.
Next, trace the hose to where it connects to the sink drain or disposal. Loosen the hose clamp (usually a small metal band with a screw) and disconnect the hose. Hold it over a bucket — water may spill out. Look inside the hose opening for clogs. You can use a straightened wire coat hanger or a plumbing snake to push through the hose and break up any blockage. Flush the hose with hot water from a pitcher or faucet to clear debris.
Check the connection point on the sink side as well. If you have a garbage disposal, make sure the hose is connected to the disposal's drain port, not just sitting inside the sink drain opening. Reconnect the hose, tighten the clamp, and run the dishwasher on a short cycle to test. If water drains and the smell is gone, the clog was in the hose.
Run a cleaning cycle with vinegar or baking soda
If the filter is clean and the hose is clear but the smell lingers, bacteria may be growing on the interior walls of the dishwasher. Fill a dishwasher-safe bowl with white vinegar and place it on the top rack. Run the dishwasher on a hot cycle with no dishes inside. The vinegar will circulate through the machine and kill odor-causing bacteria.
Alternatively, sprinkle a cup of baking soda across the bottom of the empty dishwasher and run a hot cycle. Baking soda neutralizes odors and also helps dissolve mineral buildup. You can also combine both methods: run the vinegar cycle first, let the dishwasher dry for an hour, then run the baking soda cycle.
After either treatment, leave the dishwasher door open for a few hours to air out. Run one normal wash cycle with dishes to rinse away any vinegar or baking soda residue before using it normally again.
When the problem is your home's main drain
If you have cleaned the filter, cleared the hose, and run vinegar and baking soda cycles but the sewer smell persists, the blockage is likely in your home's main drain line, not in the dishwasher itself. This is beyond a straightforward fix and usually requires a plumber with a drain snake or camera.
Signs that point to a main drain problem include water backing up into the sink when the dishwasher runs, slow draining from multiple fixtures (sink, shower, toilet), or a sewer smell coming from other drains in your home as well. Call a plumber to inspect the line. They can identify whether the clog is in the line leading from your kitchen, in the main stack, or at the street connection.
Preventing future sewer smells
Rinse dishes before loading them into the dishwasher. Food particles are the primary fuel for bacteria and clogs. You do not need to wash them thoroughly — just remove large chunks and excess sauce.
Clean the filter once a month, even if you do not notice a smell. This prevents buildup from starting. Run a vinegar cycle every two to three months as preventive maintenance. Keep the dishwasher door open for an hour after each cycle to allow moisture to evaporate; a damp machine is an ideal environment for bacteria.
Check the drain hose once a year to make sure it has not developed a kink or become disconnected. If you have a garbage disposal, make sure the hose connection is find and the disposal itself is clean — a dirty disposal can send odors back into the dishwasher.
Frequently Asked Questions
Can I use bleach to clean the sewer smell out of my dishwasher?
No. Bleach can damage rubber seals and gaskets inside the dishwasher and may react with other residues left in the machine. Vinegar and baking soda are safer and just as effective at killing odor-causing bacteria. If you want a stronger disinfectant, use a commercial dishwasher cleaner designed for the machine.
Why does the smell come back after I clean it?
The smell returns if water is still not draining completely or if the drain hose is still partially blocked. Even a small amount of standing water will grow bacteria again within a few days. Make sure the hose is fully clear and that the dishwasher drains completely at the end of each cycle. If it does not, the drain pump may be failing and need replacement.
Is a sewer smell from the dishwasher a sign the machine is broken?
Not necessarily. Most sewer smells are caused by clogs or trapped food, not by a failed part. However, if the drain pump is broken, water will not drain and the smell will return quickly no matter how many times you clean it. A plumber or appliance technician can test the pump with a multimeter to see if it is working.
Should I run the dishwasher if it smells like sewer?
Yes, running it can help flush out debris and bacteria, especially if you use vinegar or baking soda. However, if water is visibly backing up into the sink or pooling at the bottom of the machine, stop and do not run it again until you have cleared the drain hose or called a plumber. Running it with a blocked drain can force dirty water into your home's plumbing system.