Why Does My Dishwasher Smell Bad?

A dishwasher that smells like rotten eggs or wet dog is not broken — it is dirty in places you never see. Food particles collect in the filter, mold grows on the rubber door gasket, and grease coats the spray arms. The good news: a proper deep clean takes about 30 minutes of actual work and the smell is usually gone the same day.

Quick diagnosis: what kind of smell is it?

• Rotten egg / sulfur smell → food rotting in the filter or drain area. Start with Step 1.
• Musty / mildew smell → mold on the door gasket or standing water that never fully drains. See Steps 2 and 4.
• Smell only when it runs → grease and scale baked onto the heating element and interior walls. See Step 3.
• Smell plus dirty dishes → clogged spray arms — water is not reaching everywhere. See Step 5.

What you will need

• Rubber gloves
• Old toothbrush
• White vinegar (2 cups)
• Baking soda (1 cup)
• Dish soap
• Microfiber cloths or sponges
• A toothpick or thin wire

Step 1: Clean the filter (the #1 cause)

Most modern dishwashers have a removable cylindrical filter at the bottom, under the lower spray arm. This is where the smell lives.

1. Pull out the bottom rack to access the filter.
2. Twist and lift the filter out. Most unlock with a quarter-turn counterclockwise. Some have two parts (a coarse screen and a fine cylinder) — separate them.
3. Prepare to be disgusted. The filter traps food so it does not recirculate onto your dishes — which means months of trapped food is rotting in there. Scrape off the gunk into the trash.
4. Scrub it in hot soapy water with the old toothbrush, getting into every mesh pleat. For stubborn grease, soak it in hot water with a cup of vinegar for 15 minutes first.
5. Rinse and reinstall. Lock it back with a quarter-turn clockwise — a loose filter lets food bypass it and the smell returns.

Do this monthly and most dishwasher odors never start.

Step 2: Scrub the door gasket

The rubber seal around the door stays damp and dark — perfect mold territory.

1. Open the door and inspect the gasket all the way around, including the bottom edge where gunk hides.
2. Wipe it down with a cloth dampened with hot soapy water, then go over it again with the toothbrush dipped in vinegar for any black spots (mold).
3. Pull the gasket gently away from its channel and clean behind it — this hidden groove collects astonishing amounts of slime.
4. Dry it with a clean cloth. Leaving it wet just restarts the mold cycle.

Step 3: Run the vinegar + baking soda deep clean

This two-stage cycle dissolves grease, scale, and odor-causing film from the entire interior.

1. Make sure the dishwasher is empty. Remove all dishes and racks if they lift out easily (optional but lets you scrub the tub walls).
2. Vinegar cycle: place 2 cups of white vinegar in a dishwasher-safe bowl on the top rack. Run the hottest, longest cycle with no detergent. The vinegar cuts grease and dissolves mineral scale throughout the machine.
3. Baking soda cycle: when the vinegar cycle finishes, sprinkle 1 cup of baking soda across the bottom of the tub and run a short hot cycle. This deodorizes and scrubs away the loosened film.
4. Leave the door cracked open after the cycle so the interior dries completely.

Step 4: Check for standing water

After a cycle, there should be almost no water left in the bottom. If a puddle remains:

1. Check the drain filter area for a blockage (see Step 1).
2. Check the drain hose under the sink — it should loop up high (an air gap or high loop) before connecting to the disposal or drain. A hose lying flat lets dirty sink water flow back into the dishwasher.
3. Check the garbage disposal connection. If the dishwasher drains through the disposal, run the disposal before starting the dishwasher — a full disposal blocks the dishwasher drain.
4. Persistent standing water with a bad smell can mean a failing drain pump — that is a repair-or-replace decision (see “when to call a pro”).

Step 5: Unclog the spray arms

If dishes come out dirty and the machine smells, the spray arms may be blocked.

1. Remove the arms — most lower arms lift straight off; upper arms usually unscrew or unclip.
2. Clear each jet hole with a toothpick or thin wire. Mineral scale and bits of food (popcorn kernels, glass shards, labels) lodge in the holes.
3. Rinse under strong water and shake — you will hear trapped debris rattling inside. Keep rinsing until it runs clear.
4. Reinstall and spin by hand to make sure nothing blocks their rotation.

What this costs

Mistakes to avoid

• Using bleach to kill the smell. Bleach + the acids in dishwasher detergent residue can create fumes, and bleach degrades the rubber gasket and stainless tub over time. Vinegar does the job safely.
• Ignoring the filter for a year. The filter is designed to be cleaned monthly. “Self-cleaning” dishwashers still have filters that need attention.
• Closing the door tight after every cycle. A sealed, damp dishwasher is a mold incubator. Crack the door open after each run.
• Pre-rinsing dishes obsessively. Modern detergent needs some food soil to work properly, and scraping (not rinsing) is enough. Over-rinsing wastes water and can actually give worse cleaning results.
• Running the disposal-drain dishwasher with a full disposal. Always run the disposal first.

Keeping it fresh

• Scrape (don’t rinse) plates before loading.
• Clean the filter monthly — set a phone reminder; it takes 3 minutes.
• Run the vinegar cycle every 2–3 months as maintenance.
• Leave the door ajar between cycles.
• Run hot water at the kitchen tap for 30 seconds before starting the dishwasher so the first fill is hot, which cleans and sanitizes better.

Frequently asked questions

Why does my dishwasher smell like rotten eggs? That sulfur smell is food decaying in the filter or drain sump. Clean the filter (Step 1) and the smell almost always disappears immediately.

Is the smell coming from the garbage disposal instead? Possibly — they share a drain. Run the disposal with cold water and lemon peels; if the dishwasher smell improves, the disposal was the source. Keep both clean.

Can I put bleach in my dishwasher to deodorize it? Not recommended. Bleach can damage the rubber gasket and stainless interior, and mixing it with detergent residues is a bad idea. White vinegar is safer and just as effective for odor.

How often should I clean the dishwasher filter? Monthly for normal use. If you can see gunk on it, you waited too long.

When to call a pro

• Standing water that will not drain after you have cleaned the filter and checked the hose — the drain pump or check valve may have failed ($150–$300 repair).
• A persistent electrical burning smell — stop using it and call for service; that is not a cleaning issue.
• Water leaking from the door or underneath — could be a failed gasket, pump seal, or inlet valve.
• The dishwasher is over 10 years old and needs frequent repairs — replacement ($500–$900 installed) usually beats another service call.