Why does my garbage disposal smell?

A smelly garbage disposal usually comes down to food that has not made it all the way down the drain. InSinkErator says "An odor from the disposer is usually a sign of food buildup,"^[1] and food particles can collect in the grind chamber and in the baffle, the rubber splash guard in the sink opening.^[1][2] Grease makes it worse by holding that food in place. Cleaning it out is a short job, and a couple of habits keep it from coming back.

The usual cause: food under the splash guard

Turn the disposal off first, and unplug it or switch off its breaker if it is wired in.^[1] Then lift the rubber splash guard with your fingers and look at its underside. That is often where the film of old food is. InSinkErator's cleaning advice starts with taking out the sink baffle and cleaning its underside with a scouring pad,^[2] then putting it back.

Do not put your fingers or hands into the disposal; turn the power off and use long-handled tongs or pliers to take anything out.^[1] A flashlight shows you what is down there without reaching in.

Flush the chamber

With the splash guard clean, flush the grinding chamber. InSinkErator's manual gives a simple method: fill the sink halfway with warm water, mix in 1/4 cup of baking soda, then turn the disposal on and pull the stopper at the same time.^[1] The rush of water carries loose particles down the drain.

Follow that with ice. InSinkErator suggests running a medium stream of cold water and feeding ice cubes mixed with lemon or lime wedges into the running disposal.^[2] The ice scours the chamber and the citrus freshens it. InSinkErator also suggests grinding citrus peels to freshen drain smells.^[1]

When grease is behind it

If the smell comes back within days, grease is the likely culprit. InSinkErator recommends a disposer cleaner, degreaser or deodorizer for odors caused by grease buildup.^[1] Then stop feeding it grease. The King George County Service Authority explains why: "When mixed in small amounts with hot water, F.O.G. flows easily. But once it cools, it hardens inside pipes."^[6] Fats, oils and grease coat the chamber and the drain, and food sticks to them.

Skip the chemical drain opener. InSinkErator lists caustic drain cleaners among the things never to put in a disposer.^[1]

Habits that stop the smell coming back

• Run more cold water. InSinkErator says to turn on the cold water first, then the disposal, and keep the cold water running for several seconds after grinding is done to flush the drain line.^[1]
• Use it regularly. Using the disposal often also helps clear scraps that would otherwise sit in the chamber.^[2]
• Grind until it is quiet. InSinkErator says not to turn the disposal off until grinding is complete and you hear only the motor and water.^[1]
• Keep grease out. Wipe greasy pans with a paper towel and put the towel in the trash.

There is a longer list in what you should never put down a garbage disposal.

Other places the smell comes from

Standing water. If water stays in the disposal after it runs, the drain may not be sloped enough. InSinkErator says the drain line should slope at least 1/4 inch per foot from the disposal to the drain connection, and that standing water left in the unit can cause early corrosion or leaks.^[1] Fixing the slope means changing the drain piping.

A slow leak. A drip at the mount or discharge tube can soak the cabinet floor, and that smells musty, not like food. To find it, fill the sink, wrap dry paper towels around the sink flange, the discharge elbow and the dishwasher connector, and let the water drain. If any towel is wet, the leak is at that connection.^[3]

The dishwasher. If the dishwasher drains through the disposal, its food passes through too. Clean the dishwasher's filter as its manual directs.

Sewer gas. A sewage smell, especially one that also comes from other drains, is not the disposal. Fairfax County's wastewater staff say sewer gas can get into a home when a fixture goes unused long enough for the water in its trap to evaporate.^[4] The county advises adding water regularly to seldom-used sinks, toilets and floor drains.^[4] If the traps are full and the odor stays, the county says the problem could be the plumbing vent, which can be plugged by leaves or birds' nests.^[4] The county notes that vent carries sewer gas out through the roof,^[4] so clearing it is not a ladder job to take on yourself.

Natural gas. A rotten-egg smell in the kitchen may not be the drains at all. Virginia Natural Gas adds an odorant called mercaptan that gives natural gas "an odor often associated with rotten eggs."^[5] If you smell gas, or the smell is near a gas range, water heater or furnace, leave the house straight away without touching light switches or anything that could spark, and call 911 and your gas utility once you are outside.^[5] Do not try to find the leak yourself.^[5]

For a smell that is in the tap water itself, see why water smells like rotten eggs.

Stop and call a pro if

• You smell gas, or a rotten-egg smell is near a gas range, water heater or furnace. Leave the house and call 911 and your gas utility from outside.
• The smell is sewage and stays after you have refilled every trap. A blocked vent or a drain problem needs a plumber.
• Water backs up into the other sink bowl or stands in the sink. See why a drain keeps clogging.
• The cabinet floor is wet, soft or stained. Find the leak and stop using the sink until it is fixed; fixing a leaking pipe under the sink covers the joints.
• You smell burning or hot plastic. Switch it off, unplug it or switch off its breaker, and have the unit or circuit checked before you use it again.
• The disposal hums, jams or trips the breaker as well as smelling. It may need repair or replacing.

Getting help on Loclis

Licensed plumbers on Loclis repair and replace disposals. Browse garbage disposal repair, garbage disposal services, find plumbers in Blacksburg, or see every plumbing answer.

If cleaning has not fixed it, describe the problem once and licensed local businesses quote it.