Hot Topics: Replacing the Trap Under the Sink

under sink trap

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For many homeowners, repairs come easy. For others, seemingly simple tasks can turn into giant headaches. When dealing with plumbing, it can be difficult to know what pieces together properly when you need to replace sections. Take a look at how these DIYers help our forum poster through the issue.

Original Post: Thought Replacing Trap Under Sink Would Be Simple - Help?

Gtexan Member

I should preface this by saying that I am aware I made a mistake here and also that the previous owners of my house did a lot of projects themselves that we have found to be done incorrectly.

Anyway, I had a slow draining bathroom sink and decided to clean out gunk that had built up. I disconnected the sink and removed the tailpiece as well as the trap. There was so much old and nasty debris that I decided it would be easier to just replace rather than clean.

Apparently this was a mistake.

I have attached a photo of the piece that I removed the trap from.

I am clearly a novice at this, but what I have found is that the traps they sell at big box stores seem to have threads on them and the expectation is that the piece shown in the photo would slot inside and have a tightening ring that screws onto the traps threads.

Clearly this is not possible with what I have here.

So the question: What is the right trap piece I need to replace?

Highlights from the Thread

czizzi Forum Topic Moderator

It looks like a normal back half of a ptrap to me, mock up how it was and send us a wider shot of what you are looking at. I fail to see an issue given the close up picture you attached. 1-1/2 in. PVC DWV Hub x Hub P-Trap-C4895HD112 - The Home Depot

Gtexan Member


Thank you for the link! Lowes did not carry traps with unions like that - (threads were on the trap itself).

I tried the piece from HD and it is a hair too big. Are the thread diameters unique to the manufacturer? I know the pipe is the right size but the threads dont' line up - just very close but a slight bit too big.

CasualJoe Member

The pictured trap is the wrong one for a sink. Here is the P trap you need along with a trap adapter.

Everbilt 1-1/4 in. Plastic P-Trap-C9700B - The Home Depot

1-1/2 in. x 1-1/4 in. PVC DWV Hub x SJ Trap Adapter-C48017HD112114 - The Home Depot

The adapter glues onto the straight 1 1/2" pipe coming from the wall and accepts the 1 1/4" trap. The tailpiece on the sink should also be 1 1/4". With this setup the new trap will be forever removeable for cleaning and/or future replacement just by loosening the plastic nuts.

Gtexan Member


What is the difference in using a 1-1/4 vs 1-1/2 trap?

To use the piece you sent, I would need to cut the pipe coming out of the wall, is that correct?

lawrosa Super Moderator

Yes, just cut the ellbow off coming out of the wall.

Glue on a trap adapter 1 1/2" (Dry fit all first to be sure trap lines up with tail piece.)

And use trap as joe shows 1 1/2...

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