(Benjamin C Tankersley for The Washington Post)

Q: No matter what I do, my garbage disposal has a foul stink in it. It’s disgusting. What’s causing it, and how can I get rid of the odor? Once the offensive odor is gone, is there some way to ensure it never comes back?

Susanne W., Tacoma, Wash.

A: Smelly garbage disposals in kitchens are more common than you might think. A large number of homeowners reach out to me on a routine basis with the identical problem.

The odor in the disposal comes from rotting food. Your garbage disposal is a machine that grinds food into a slurry. This slurry coats the inside of the cylinder chamber that contains the spinning, grinding teeth.

If you have a disposer that smells, then you’re not removing all the sludge from the insides of the disposal each time you use it. What’s more, you could be creating clogs in your plumbing drain lines by not fully rinsing the disposal with enough water after each use to carry the sludge to the city sewer or your septic tank.

Cleaning the disposal is not too hard, but it takes a few steps. You need to rehydrate any dried food slurry on the side walls of the disposal. You do this by installing the stopper in the large hole at the bottom of the sink. Fill up the sink one-third or halfway with warm water.

Leave the faucet running, pull the stopper out and immediately switch on the disposal. The spinning grinders create a vortex of water in the disposal, getting all surfaces nice and wet. Wait 20 minutes and repeat this process. The softer the dried food becomes, the cleaner the disposal will be after the final step of the cleaning process.

Wait another 20 minutes and repeat the process, but this time, before you switch on the disposal, squirt into the water a quarter-cup of liquid dish soap. Squirt more soap into the disposal as the water runs from the faucet so you create a spinning slurry of soap suds in the disposal.

Adjust the water flow from the faucet to a trickle so the sudsy slurry comes to the top of the disposal. Add more soap if necessary. Keep the disposal on, allowing the slurry to scour the inside of the disposal.

Turn off the disposal after 30 or 45 seconds, then rinse away all the soap. To prevent future odor, you need to fully rinse the disposal after each use. Each time you finish grinding food, fill the sink halfway with clear water. Pull the stopper and turn on the disposal to spin the rinse water around the insides of the machine. This large amount of water helps flush all the drain pipes, preventing future clogs.

I’ve got a great video for you at my AsktheBuilder.com website showing exactly how to use liquid dish soap to clean a disposal. Just go to: http://go.askthebuilder.com/cleandisposal.

Tim Carter can call you on the phone FREE to solve your problem. Go to his website and fill out the form at https://www.askthebuilder.com/ask-tim/.