A clogged kitchen sink is nearly always grease, food residue and soap scum packed into the P-trap or the drain line just beyond it. The reliable order is: plunge properly (blocking the second basin and the dishwasher line), then clean out the P-trap, then use a drain snake. If a disposal or dishwasher is connected, check them too. Chemical drain cleaners are a last resort.
Quick checks first
Remove the strainer and any visible debris. Run hot tap water briefly to see whether the sink drains slowly or not at all. A slow drain responds to the steps below; a sink that gurgles or backs up into the other basin may have a deeper blockage. For a slower drain in general, see how to unclog a slow drain.
Plunge it properly
- Seal everything else
For a double sink, block the second drain with a wet cloth or stopper. If there is a dishwasher connected, clamp or pinch its drain line if you can.
- Fill the basin with a few inches of water
The water covers the plunger cup so it can push and pull water, not air.
- Use a flat-bottom cup plunger
Press down and pull up firmly 15 to 20 times, then check whether the water drops. Repeat a couple of times.
Clean the P-trap
- Put a bucket under the trap
The U-shaped pipe under the sink holds water and sludge.
- Loosen the slip nuts by hand
Remove the trap and empty it into the bucket. Use gloves.
- Clean it and refit it
Scrub out any grease and debris, inspect the washers, and tighten the nuts snugly by hand. Run water and check for leaks.
If the blockage is farther back, a trap this clean points to the drain line behind the wall.
Use a drain snake
A hand-cranked drain auger (a 15 to 25 foot one is enough for most kitchen drains) reaches clogs past the trap. Feed it into the pipe, crank until you hit resistance, work through it and pull out the debris, then flush with hot water. Avoid forcing it hard, and stop if it will not move; a plumber has better tools.
If you have a disposal or dishwasher
A jammed or clogged disposal holds the water back. See garbage disposal jammed and disposal won’t turn on. A dishwasher shares the same drain, so if your sink is blocked the dishwasher may fail to drain too; see dishwasher won’t drain. Turn off the disposal’s power before putting a hand or tool near it.
Why to avoid chemical cleaners
Caustic drain openers can damage older pipes and fittings, release heat or fumes, and are hazardous if they splash. If a chemical cleaner has already been used and failed, tell the plumber or wear eye and skin protection before opening the trap, because the water in it may still be caustic. A plunger, trap clean-out and snake solve most blockages without them.
When more than one drain is slow
If the bathroom sink, shower or washer also drains slowly or gurgles, the blockage may be in the main line or the vent, not the kitchen branch. Sewer smells in the house can point the same way; see sewer smell in the bathroom and common plumbing problems. That is a plumber call.
Keeping it clear
Wipe greasy pans with a paper towel before washing, bin the fat rather than pouring it down the drain, use a sink strainer, and flush the drain weekly with hot (not boiling) tap water and a squirt of dish soap. Avoid sending coffee grounds, rice, pasta and fibrous peelings down the disposal.
When to call a plumber
If the plunger, trap and snake do not work, if water backs up into other fixtures, or if the trap or pipes leak, call a plumber. For a toilet blockage, which needs different tools, see toilet clogged and plunger not working.
