Kitchen sink drains slowly

Symptoms

• Water empties much slower than it used to
• Gurgling sounds as it drains
• Smell of old food near the drain
• Water backs up when the dishwasher runs

Likely causes

• CommonGrease buildup coating the inside of the pipeGrease cools and hardens on pipe walls, gradually narrowing the opening.
• CommonFood particles collecting in the trapEven with a disposal, some particles settle in the curved trap.
• PossibleClogged garbage disposal or its drain lineA partially clogged disposal can slow drainage for the whole sink.
• Less commonVent blockage causing slow drainage with gurglingA blocked roof vent can create a partial vacuum that slows draining.

What to do

1. Stop pouring grease or oil down the drain going forward, letting it cool and throwing it in the trash instead.
2. Run hot water for a minute to see if it helps temporarily loosen grease buildup.
3. Try a mix of baking soda followed by vinegar down the drain, let it sit 15 minutes, then flush with hot water.
4. Plunge the drain, covering the second basin's drain if it's a double sink, and the dishwasher air gap if present.
5. If it's still slow, remove and clean the P-trap under the sink, checking for grease or food buildup.
6. If the sink has a garbage disposal, make sure it isn't jammed or clogged, since that can slow drainage for the whole sink.
7. For a stubborn clog, feed a hand-crank drain snake into the trap arm toward the wall.
8. Once cleared, run hot water for a couple of minutes to confirm normal flow.

Tools and parts

• Plunger
• Hand-crank drain snake
• Baking soda
• Vinegar
• Adjustable pliers

When to call a pro

Call a plumber if cleaning the trap and snaking the line doesn't restore flow, or if the problem keeps coming back.

Safety