How to repair kitchen sink pipes

Written by shane grey
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How to repair kitchen sink pipes
Despite drain assemblies' awkward, under-sink location, removal and replacement are quick and straightforward. (Jupiterimages/liquidlibrary/Getty Images)

Kitchen sink drain assemblies commonly consist of threaded, plastic drain pipe components. A roughly L-shaped pipe connects the wall drain to a curved P-trap, and a straight pipe extension attaches the P-trap to the sink's strainer. Fortunately for the novice plumber, standard plastic drain pipes connect via threaded fittings that loosen and tighten by hand or with basic tools. Importantly, under-sink drain assemblies are available in either 1 1/4 or 1 1/2 inch diameters; if you're replacing an existing drain assembly, measure the pipes' diameter prior to purchasing replacement components.

Skill level:
Moderately Easy

Things you need

  • Bucket
  • Rags
  • Adjustable wrenches or pipe wrenches
  • Replacement drain assembly

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  1. 1

    Place a bucket beneath the kitchen sink's drain assembly to catch water; the assembly's P-trap holds waste water, so you must use a bucket to catch this water during drain repair. Wrap a rag around the nut that secures the P-trap to the sink basin extension.

  2. 2

    Twist the nut counterclockwise to loosen. If you cannot loosen the nut by hand, attach an adjustable wrench or pipe wrench to the nut and loosen the nut with the wrench. Wrap the rag around the nut that secures the P-trap to the wall drain extension. Loosen the nut by hand or with a wrench.

  3. 3

    Allow water to drain into the bucket from the P-trap. When the water slows to a trickle, slide the P-trap away from the extension pipes and remove the P-trap from the drain assembly. Dump water that remains in the P-trap into the bucket and discard the P-trap.

  4. 4

    Loosen and remove the nut that connects the sink basin extension pipe to the sink strainer. Loosen and remove the nut that connects the wall drain extension pipe to the wall drain pipe. Discard the old pipes.

  5. 5

    Press the flange end of the replacement sink basin extension pipe into the sink strainer's opening. Slide the pipe's washer onto the pipe's smooth end, followed by the nut. Press the washer and nut against the strainer's threads and twist clockwise to tighten the nut onto the strainer and secure the extension pipe to the sink basin.

  6. 6

    Slide a washer and compression nut onto the smooth end of the replacement wall drain pipe extension. Position the nut's threads facing the curved end of the pipe. Slide the wall drain pipe extension's second nut onto the smooth end of the pipe with the threads facing the smooth end of the pipe. Slide the second washer onto the pipe.

  7. 7

    Insert the smooth end of the wall drain pipe extension into the wall drain and thread the extension's nut onto the wall drain's male threads. Position the replacement P-trap's short side beneath the extension pipe's curved end. Thread the extension pipe's loose nut onto the P-trap.

  8. 8

    Rotate the P-trap to position its open end beneath the basin extension pipe. Slide a compression nut and washer onto the open end of the basin extension pipe. Slip the basin extension pipe into the P-trap and slide the washer and nut against the P-trap's threads.

  9. 9

    Thread the extension pipe's nut onto the P-trap. Tighten all connections until hand tight. Run water through the drain assembly to check new connections for leaks.

Tips and warnings

  • If the replacements are too long, cut pipes to fit with a hacksaw.
  • Compression nut fittings do not require pipe dope or thread seal tape; do not apply dope or tape to compression connections.

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