I've been trying to replace a corroded bathroom sink drain.

From my wall I have a 1 1/2" threaded PVC or plastic pipe. I have been attempting to attach this to the elbow from my p-trap kit using a slip joint reducer nut and washer. The nut is the right size and threading and thus can be attached on it's own. When I use the washer however the threading on the nut can't reach the threading on the pipe.

On the pipe from the wall there is a small lip between the edge of the pipe and where the threading begins. I can see the old corroded nut is much deeper which overcame this gap.

I either need a deeper reducing nut, or a thinner washer, neither of which I can find at my local Lowes (the only option in town where I live). Although I can find differently branded products online, they all appear to have the same design as the nut and washer I have.

Picture of pipe from wall showing threading lip

This picture is using a different washer than the one it came with as I thought it was a little thinner, but it did not work.

How can I find the part I need, or do I need to seek a different solution altogether?

  • It would help if you added a photo of the existing pipe and nut that is creating the problem for you. Commented Jun 17, 2021 at 16:35
  • @Programmer66 Typed this up on the computer and have been trying to edit in picture on mobile since posting. Phone being a pain though. Coming soon.
    – Fr33dan
    Commented Jun 17, 2021 at 16:40
  • Cut or grind off the outer portion of the male fitting. Done and done.
    – isherwood
    Commented Jun 17, 2021 at 16:48
  • @isherwood If I had tools to make a clean cut/grind I probably would have tried that already. I'm really hoping to spend a couple of bucks on a correctly sized nut or adapter than whatever a good saw/grinder is gonna cost me.
    – Fr33dan
    Commented Jun 17, 2021 at 16:53

3 Answers 3


That chromed metal nut is very shallow. It doesn't appear to be intended for use on a plastic thread. Maybe a plastic nut will serve you better. Here are some other ideas:

  • Mix and match: Choose the best among the old and new parts. Maybe you can use the old nut with the new seal for example.
  • Modify: the male adapter on the wall pipe does appear to have a rather long "nose" without threads. Remove some of it. The sealing surface is the inside corner of the adapter and the sealing washers are somewhat forgiving so your trim work doesn't have to be pristine. Try a utility knife, hand sanding block or sandpaper wrapped on or glued to a wood block, powered sander or sanding attachment in a drill, hack saw or coping saw, a rotary ("Dremel") tool.. Even a large sprinkler pipe cutting tool could work. Surely you already have or "need" one of these! If you're going to use a utility knife then warming the pipe with a hair dryer may make the cutting just a little easier.
  • Replace: Cut off the existing male adapter and replace with one that is compatible with the other parts. It's best to replace with the same kind of plastic (ABS or PVC probably), however, "transition cement" purports to allow mixing of ABS and PVC parts. (Not for use on pressurized systems, read and follow the label instructions, etc. Personally, I go to great lengths to avoid this stuff -- but it is out there.)
  • You partially had the solution in the suggestion to use a plastic nut. I had been looking for a plastic reducer nut, this time an older gentleman asked me if I needed help and suggested I just use a regular plastic 1 1/2" slip joint nut with the reducer washer (as opposed to a specific reducer nut). A little bit of the washer is exposed but it is drip free.
    – Fr33dan
    Commented Jun 17, 2021 at 20:13

I believe you are using leftover parts or not assembling the Reducter Nut correctly for the Reducer Nut you are linking to. There are reducer that use the lip tub (the white piece in your picture), but those normally use a flat washer. Your "red" washer should be taper with the small end going into the 1 1/2" pipe.

See diagram below: "Picture frow Lowe website"

enter image description here

There are reducers that have the lip insert like the white piece in your picture but these normally use a flat washer.

  • This is how I have assembled it. The reducer nut came with a red rubber washer. When the red one didn't work in this configuration I bought the white one hoping it would be thinner. It is the same shape as shown, you are looking at the flat end in the picture and it tapers into the existing pipe.
    – Fr33dan
    Commented Jun 17, 2021 at 18:31

I would go to Home Depot, Lowes, Of a large Hardware store like ACE and tell them that you have an 1-1/4" "P" trap that you want to adapt to an 1-1/2" drain fitting that has a nut and washer. Take a picture of just what you posted here and they will get you what you need to make the connection.

They used to make a reducing nut that would adapt the drain you have to the 1-1/2" adapter that you show in the picture but I do not know if they are still available. Hope Go to the store and they will get you what you need. Good luck

  • I've had several trips to the store and gone over the situation with their staff several times. Twice they sent me home with the actual wrong thing for what I needed. They finally got me the nut and washer which is technically correct from a threading and input/output stance, but because my existing pipe has that lip this one option they have for this does not work. At this point unless I want to cut the wall pipe and attach new threading I'm almost positive I need to buy something online, but need to figure out how to discern what I purchase won't have the same problem.
    – Fr33dan
    Commented Jun 17, 2021 at 18:43

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