Just throw a lemon in there, my aunt said, like it was the most obvious thing in the world. She has never once had a sink that smelled. Meanwhile I had been buying a bottle of disposal cleaner every two months.

What Actually Causes the Smell

It is rarely the disposal itself. It is the film of food residue on the rubber splash guard and along the walls of the chamber. That film sits there warm and wet and it grows things. Most of the odor comes from up top near the opening, where people never scrub.

The Penny Fix

1. Drop in a handful of citrus peels, lemon or orange, whatever you just used.
2. Turn on cold water and run the disposal for about fifteen seconds. Cold water, not hot. Hot water melts fats that then re solidify further down the pipe.
3. Add a few ice cubes and a tablespoon of coarse salt and run it again. The ice scours the walls and the salt scours the blades.

That is it. Once a week keeps it neutral. The citrus oil cuts the grease film that holds the smell.

Do Not Skip the Splash Guard

Pull the rubber flap up and wipe underneath with a soapy sponge. Rinse with cold water and you are done. This is the step that actually fixes it.

I went back to the store brand cleaner once out of habit and it worked about as well as the lemon peels. I have not bought it since.