Symptoms
- Water doesn't drain at all from either basin
- Standing water stays at the same level
- May be accompanied by a bad smell
- Garbage disposal runs but doesn't help drainage
Likely causes
- CommonHardened grease and food clog in the trap or drain lineGrease solidifies and traps food particles into a dense clog.
- PossibleObject stuck in the disposal or drain lineUtensils or produce stickers can lodge in the line.
- PossibleClog in the shared branch line (double sink)A clog between the two basins backs up whichever side is run.
- Less commonBlockage further down toward the main lineMore likely if other drains in the house are also slow.
What to do
- Turn off the garbage disposal at the switch and do not run water into it while troubleshooting.
- Plunge the clogged basin firmly, blocking the other basin's drain and the dishwasher air gap with a wet rag first for good suction.
- If that doesn't work, place a bucket under the sink, loosen the P-trap's slip nuts, and remove the trap to check for a clog.
- Clear any debris found in the trap and inspect the trap arm going into the wall for further blockage.
- If the trap was clear, feed a hand-crank drain snake into the wall-side drain opening and work it in a few feet at a time.
- Reassemble the trap, run hot water, and confirm both basins drain normally.
- If a double sink still backs up between basins, the shared tee fitting may need to be checked as well.
Tools and parts
- Plunger
- Adjustable pliers
- Bucket
- Hand-crank drain snake
When to call a pro
Call a plumber if the clog is beyond the trap and a hand snake can't reach or clear it.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.