How to replace an elbow joint below a sink

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How to replace an elbow joint below a sink
Fix a clogged drain by replacing the elbow joint below the sink. (fillet d"eau image by Alexandre from

The elbow joint below a sink drain is designed to catch small items such as rings if they accidentally fall into the drain. Also, the elbow joint is designed so that clogs form there, making unclogging the pipes easier than if the clog happened in the plumbing behind a wall or under a floor. If the elbow joint is clogged, has become corroded or has developed a leak, replacing it is something almost any homeowner can accomplish.

Skill level:

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Things you need

  • Bucket
  • Adjustable wrench
  • Bottle brush
  • Rags
  • Elbow joint
  • Rubber gaskets
  • Teflon tape
  • Nuts

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  1. 1

    Turn off the water valve that serves the sink. Bail out any standing water in the sink above the elbow joint. Disconnect the bar to the pop-up drain stopper if there is one.

  2. 2

    Slide the bucket under the existing elbow joint. The bucket should hold at least a gallon and be shallow enough to slide freely under the elbow joint so you can remove it if it is full of water. Water will come out of the pipes when you remove the joint if it is not already leaking.

  3. 3

    Loosen the nuts holding the elbow joint on each end with a wrench and remove the joint and the old gaskets. Disconnect the end of the elbow joint nearest the sink drain first then the far end. Let the water run out of the drain and elbow joint into the bucket as you work.

  4. 4

    Remove the bucket and empty it or set it aside where you run no risk of spilling it.

  5. 5

    Clean out the pipes that are now open. It is likely there is some build-up and you can remove it with a bottle brush and some rags.

  6. 6

    Wrap the threads of the new elbow joint with Teflon tape. Install the new rubber gaskets in place of the old ones.

  7. 7

    Install the far end of the elbow joint first then the end nearest the sink drain. Hold the end of the elbow joint in place, slide the nut over the threads and tighten by hand. Tighten slightly with the wrench but not hard enough to break the pipes.

  8. 8

    Reconnect the bar to the pop-up stopper if there is one. If the stopper is not a pop-up type, locate it. You will use it for testing.

  9. 9

    Wipe the pipes under the sink with paper towels to remove any water drops then test for leaks. Plug the drain with the stopper and turn on the water valve to the sink. Turn on the cold water and fill the sink about one-quarter full.

  10. 10

    Let the water drain out while observing the pipes under the sink for leaks. Even if you do not see a leak, wipe the pipes with paper towels again. If there is water on the towels, there is a leak.

  11. 11

    Fix any leaks by removing the new elbow joint completely and removing the Teflon tape. Dry the threads and wrap them with new Teflon tape. Replace the elbow joint and tighten the nuts slightly more than you did the first time.

  12. 12

    Repeat Steps 9 and 10 to test for leaks.

Tips and warnings

  • Perform this task while the hardware store is open in case you need to go there to buy parts unexpectedly.
  • If there is an extension tube between the sink drain pipe and the elbow joint, it probably will not need to be replaced. However, inspect it carefully and replace it if necessary.
  • If you cannot get the leak stopped, call a professional plumber.
  • Do not use a pipe wrench, which is too large for the pipes under a sink and may strip the nuts.
  • Test for leaks using only cold water to avoid scalding.

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