How to Clear a Clogged Sink Drain Trap

Plumber working on pipes under kitchen sink
Paul Bradbury / Getty Images
Overview
  • Total Time: 10 mins
  • Skill Level: Beginner

It's tempting to call your local plumber when the kitchen sink is stopped up with dirty dishwater, but before spending the money, you should know that it's almost always a rather easy fix. In most cases, it takes just a few minutes and requires tools you probably already have on hand.

What You'll Need

Equipment / Tools

  • Plastic container
  • Drain plunger
  • Bucket
  • Sponge
  • Channel-type pliers

Materials

  • Paper towels or rags

Instructions

  1. Try Plunging First

    First, try to clear the drain using a rubber cup-style plunger. Bail out all but 1 to 2 inches of water in the sink, using a plastic container.

    Place the cup of the plunger over the drain opening and pump up and down rapidly several times. Quickly pull the plunger off the drain opening. There is a good chance that this will dislodge whatever was clogging the drain. If so, then run water for a couple of minutes to flush the debris down into the main drain.

    If the clog remains, bail and sponge out as much of the water in the sink as you can, and proceed to disassembling and clearing out the drain trap.

  2. Examine the Trap Assembly

    Place a bucket or other container under the trap to catch water, and have a few paper towels or a rag on hand to wipe up spills. Examine the parts of the drain. The large nuts at the pipe connections are what you'll be loosening to disassemble the main drain assembly. For a kitchen sink, this typically includes a two-part waste piece (if the sink has two basins), a trap, and a trap arm. There will also be a vertical pipe (called a tailpiece) coming down from one or both sink basins, or a discharge pipe from the garbage disposer; typically, these don't have to be removed.

    Place a container under the trap to catch water
    Aaron Stickley
  3. Loosen the Drain Trap

    The drain trap is the J-shaped piece of pipe at the lowest point in the drain assembly. Because of the sharp bend in the trap, it is by far the most common place for drain clogs to occur.

    Loosen the nut at each end of the trap. You may be able to loosen them by hand; if not, use channel-type pliers. Unscrew the nuts all the way, then slide each nut and its washer upwards a little bit on the pipe. Support the trap from below with one hand while you remove the second nut to prevent the trap from falling down.

    The trap is full of dirty water and sink waste. Handle it carefully, and make sure there is a bucket underneath to catch the water.

    Unscrew Kitchen Trap
    Aaron Stickley
  4. Remove the Trap

    Pull the trap straight down,then tip it over to drain the contents into your container. If you have emptied the sink completely, there should not be much water or mess falling when you remove the trap; otherwise, there may be a lot.

    Remove kitchen trap
    Aaron Stickley
  5. Clear the Trap

    Examine the trap carefully for debris. You can use a toothbrush or other small utility brush to clean it, or you can flush it with water at another sink. If there was a noticeable clog here, and the other drain parts seem clear, you've likely found the clog and can reassemble the trap. Otherwise, continue with the disassembly.  

    Clear clogged trap
    Aaron Stickley
  6. Remove the Trap Arm

    The trap arm is the horizontal pipe with the curved end that runs into the branch drain in the wall. This is another possible location for a clog. Loosen the slip nut that secures the trap arm to the branch drain. Extract the trap arm to examine it for clogs and remove any debris you find. If a noticeable clog was found here, you don't need to look further. 

    Remove the kitchen trap arm
    Aaron Stickley
  7. Remove the Two-Part Waste

    The two-part waste pipe is the horizontal pipe that connects two sink basins or the garbage disposer to the drain trap. Two slip nuts are holding it in place; unscrew them and remove the pipe. Examine it for clogs and remove any debris you find.

    If none of these locations has produced the clog, your clog may lie in the branch drain behind the wall. This is a little more serious problem, though you may be able to fix this yourself, too, by using a drain snake

    Remove two part waste
    Aaron Stickley
  8. Reassemble the Drain

    After you’ve checked all parts and removed any clogs, you can put the kitchen sink drain back together in reverse order. Tighten all of the slip nuts by hand, then use the pliers to give them a tighter seal (about 1/8 of a turn).

    Turn on the water to verify that the drain is clear and draining. Flush plenty of water through the drain.

    Check for leaks. If the drain parts leak at all, slightly tighten the joints again with pliers another 1/8 turn. Drain pipes are not under pressure, so it should not be necessary to tighten the slip nuts too far. 

    Place the stopper in the sink and fill it with water. Release the stopper and watch beneath the sink to verify that the drain joints are not leaking. 

    If the clog remains after your work on the drain trap, then the problem is deeper in the drain system and you'll need to use a drain snake or call a plumber.

    Be careful not to overtighten the slip nuts. They're made of cheap plastic and can easily crack under the force of pliers.