Two kinds of smell
A sour, rotting-food smell usually comes from residue in the disposal, the underside of the splash guard, or grease and food sitting in the trap. It is unpleasant but local, and cleaning usually helps.
A sewer smell, often described as rotten eggs, is different. It suggests sewer gas is getting past the trap. That can happen when the trap loses its water seal, when a slip joint or connection under the sink is loose, or when a vent problem lets the trap siphon dry. A sewer smell is worth having checked.
Narrowing it down
- IfSmell is strongest at the disposal openingThenClean the splash guard and grinding chamber with the power off.
- IfSmell is inside the sink cabinetThenLook for a loose trap nut, a slow drip or a damp cabinet floor.
- IfSmell appears after the sink drains with a glugThenThe trap may be siphoning; a plumber should check the vent.
- IfSewer smell in several roomsThenCall a plumber; the issue may be beyond the kitchen.
- IfYou smell gas rather than sewageThenLeave the house and call 911 or SoCalGas from outside.
Cleaning the likely sources
Disposal splash guard
With power off, lift or turn the rubber guard and scrub its underside with a brush and dish soap.
Grinding chamber
Still with power off, wipe what you can reach with a long brush. Run cold water and the disposal afterwards.
Basket strainers
Remove and scrub both, including the rubber gaskets.
P-trap
If the smell lingers, open the trap over a bucket and rinse out grease and food.
Dishwasher filter
A dirty filter can smell like the sink. Clean it according to the manual.
Tell the plumber
- Whether the smell is sour food or sewage.
- When it appears: always, after draining, or after the dishwasher runs.
- Whether the sink is also slow or gurgles.
- Any recent work under the sink, such as a new disposal or faucet.
Common questions
Can a trap dry out in a kitchen sink?
It is less common than in a rarely used guest bath, but a vent problem can pull water out of the trap when the sink drains. Running water should refill it; if the smell returns, have the venting checked.
Should I pour bleach down the drain to kill the smell?
It may mask the odor briefly but does not remove grease or fix a seal problem. Never mix bleach with other cleaners or drain openers.
Could the smell mean a broken drain pipe?
It can, especially if the smell is in a wall or under the floor. A camera inspection or a plumber's inspection under the sink can help find it.
General information for Fullerton, not a quote or professional advice. In an emergency, call 911.