My dishwasher started smelling like a damp basement. I ran empty cycles with vinegar. I bought those little dishwasher cleaning tablets. Nothing worked. Then I discovered my dishwasher had a filter I was supposed to be cleaning. I had lived in that apartment for two years and had no idea it existed.

Where the filter is and why it smells

Most dishwashers made in the last 15 years have a removable filter at the bottom of the tub, under the lower spray arm. It catches food particles so they do not get recirculated onto your “clean” dishes. If you never clean it, those food particles sit there in warm, wet darkness and decompose. That is the smell.

To find yours: pull out the bottom rack. Look at the floor of the dishwasher. There will be a cylindrical piece, usually near the center, that twists counterclockwise and lifts out. If you are not sure, Google your dishwasher model plus “filter location.”

How to clean it (it is worse than you think)

The first time I pulled mine out, it was coated in a grayish-pink sludge that smelled exactly like the odor I had been trying to eliminate. Here is what to do:

1. Remove the bottom rack. Twist the filter counterclockwise and lift it out. Some models have a secondary flat filter underneath.
2. Rinse it under hot running water. Use an old toothbrush to scrub the mesh screen — the tiny holes trap the worst gunk.
3. Fill your sink with hot water and a squirt of dish soap. Soak the filter for 10 minutes, then scrub again.
4. Rinse thoroughly and snap it back in. Make sure it clicks into place — a loose filter lets debris bypass it entirely.

I do this once a month now. The smell has not come back.

While you are down there

Check the spray arms. The little holes on the top and bottom spray arms get clogged with mineral deposits and food bits. If you see white crust or dark specks in the holes, poke them out with a toothpick. Clogged spray arms mean weak water pressure, which means dirty dishes and more food particles left behind to feed the filter gunk cycle.

Also wipe down the rubber seal around the door with a damp cloth. Food residue collects in the fold and molds over time. That is another smell source people blame on the filter.