Dishwasher Smells Like Sewage: Where It’s Really Coming From

When your dishwasher smells like sewage, the machine itself is usually not the problem. Rotting food and a drain that won’t flow right cause most of these. You can check the likely causes in one evening with a flashlight and a cup of vinegar.

Start With a Sniff Test

Open the door and smell the tub. Then lean over the sink and smell the drain. If the sewer smell hits harder at the sink, the dishwasher may be innocent and the problem sits in your plumbing. If it hits harder inside the tub, keep going.

Run the sink tap for a minute before you sniff. A dried-out trap lets sewer gas climb the drain, and a minute of water refills it.

Rule Out Gas

Natural gas carries an additive that smells like rotten eggs. If the smell fills the kitchen, or you have a gas stove nearby, treat it as gas until you know better. Leave the house, skip the light switches, and call from outside. Enbridge Gas runs a 24-hour emergency line if you need it.

Clean the Filter and the Spray Arms

Old food builds up in the filter and inside the spray arm holes, and it gives off a smell close to sewage. Pull the filter, scrub it, and poke the spray arm holes clear with a toothpick. Our dishwasher filter cleaning guide shows the steps.

Wipe the door seal and the bottom edge of the tub too. Grime hides there, and the filter alone won’t fix it. If the smell keeps coming back after a full cleaning, dishwasher repair is the next step.

Dishwasher Smells Like Sewage Only While It Runs?

Hot water and steam wake up smells that sat quiet between cycles. That points to standing water or grime hiding in the tub. Check the bottom after a cycle. A little water near the filter is normal. A puddle isn’t, and stagnant water breeds bacteria fast. Our dishwasher not draining after cycle guide covers what to do.

Check the Drain Hose and the High Loop

The drain hose carries dirty water out to the sink drain or disposal. Grease and food clog it slowly, and a kink does the same job faster. Look under the sink and follow the hose. You want a high loop, where the hose rises up under the counter before it drops to the drain. Without that loop, dirty sink water can flow back into the dishwasher.

Some installs skip the high loop. If the smell started right after a new install, look here first.

Clean Out the Garbage Disposal

If your dishwasher drains through a disposal, the disposal often causes the smell. Scraps sit in it and decay, and the odor backs up through the connection. Scrub the rubber splash guard, run the disposal with cold water and a handful of citrus peels, then flush it with hot water. Related reading: Bosch Dishwasher E24 Error: What It Means and How to Fix It.

Run a Deep Clean Cycle

Set two cups of white vinegar in an upright dishwasher-safe container on the bottom rack. Run a hot cycle with the tub empty. KitchenAid recommends this vinegar rinse, or a dishwasher cleaner tablet if you prefer.

Skip the bleach unless your manual says it’s safe for your tub, and never mix it with vinegar. Don’t pour chemical drain cleaner into the machine either. It’s caustic and damages rubber seals and pump parts.

Dishwasher Smells Like Sewage Even After You Clean It?

Cleaned everything and the smell still shows up? Then the source sits past the dishwasher: a partial clog in the drain line, or a blocked plumbing vent inside the wall. That’s plumber territory. A Toronto plumbing guide gives the same advice: call a plumber to trace where the sewer gas comes from.

A failing drain pump can also hold water in the tub and keep the smell alive. Our dishwasher troubleshooting guide covers what to check, and a technician can confirm the pump.