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The drain under the bottom of my sink, and the upwards section of the trap that is supposed to meet it, are misaligned—but by much less than other examples I can find online, including here. Looks to be about a quarter-inch off from a perfect fit. I’m hoping that this means there’s an easier way to fix it than getting new pipe and rerouting.

The “solution” apparently used by the contractors the previous owner hired was to jam a small section of pipe—a T for connecting the dishwasher drainage—in at an angle. This works poorly and produces a slow leak—that occasionally becomes a fast leak if the T section slips out of position, which happens every now and then.

Here’s what that looks like at the best of times:

sink drain into a T that is angled to try to meet misaligned trap

The T section there barely covers the gap—the overlap between the T section and the pipes above and below is about a sixteenth of an inch.

Here’s what it looks like if I disconnect the T section from the sink drain, and let it come straight out of the trap:

same sink drain with T straight out of trap, offset from sink drain

There is a little bit of wiggle in the pipe with the trap, so it can get a little closer than this, but not much; certainly not enough to close the gap at a straight shot. And anyway it won’t stay like that; it’ll just sag back down and the T section will slide out of place and dump water on the floor.

Notably, neither of these two connections are threaded. The T section and the trap each have a collar you can tighten (and tightening either too much cause the pipe it’s supposed to be clamping onto to instead pop out).

So the question is, what is the easiest way to solve this myself? Is there any way I can solve this myself? A “solution” being one that keeps water inside the pipe. Currently I can keep most of the water inside the pipe, but inevitably a little leaks out.

Various ideas I’ve had, that I don’t know enough to judge the merits of:

  • I know PTFE tape is mostly for threads, so I don’t think it’s appropriate at these joins, but is there something I can put in there?

  • Or wrap around it? I don’t love the sound of that since I’d worry water would collect in there but open to being corrected on that concern.

  • Or—much better—is there exist anything I could buy to actually have a proper seal at this kind of angle?

  • I note that there are threads on the pipe coming out of the sink itself—is any of that adjustable?

  • Or any way to move the trap that little bit closer to the wall? I suppose ultimately I could replace that pipe with a slightly shorter one, though I’m not sure I’d even know how to pick out the right one.

I’m fairly handy, but know little about plumbing. I don’t even know what here is something I might be able to successfully fix, and what should be left to professionals. I also live in a small apartment with limited workspace, and somewhat limited tools—pliers, wrenches, hammers, screwdrivers, levels, measuring tape, that sort of stuff, plus a power drill and a Dremel.

Finally, this is what the rest of the piping looks like, in case there’s anything relevant back there:

another angle under the sink, showing the rest of the pipe the trap connects to

As requested, more images of the black pipe in the back. Also visible are the drain hoses from the dishwasher. The black pipe comes out of the wall to the left of the sink, and elbows down to the vertical segment seen previously, and then elbows into the wall behind the sink.

further back under the sink, showing the bottom of the vertical pipe elbowing into the wall

upward-looking shot under the sink, how the “vertical” pipe comes horizontally out of the wall to the left before elbowing down to be vertical

The left of this photo is another wall, so this pipe is coming out of the wall there above the wood seen in the upper-left of the photo.

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  • What's with the check valve and what are the two things feeding it? Can you provide a wider shot showing more of those and more of the main vertical pipe? Are you in a high rise building? I share the advice you already got: replace everything with plastic swivel and slip joints. But you may not be allowed to do that if you're subject to building rules.
    – jay613
    Commented Apr 22 at 21:02
  • @jay613 The check valve connects to the two drain hoses from the dishwasher, which connect to the T and go out the same drain as the sink. I really don’t think there’s much to see in that direction, it’s just those two hoses going into the wall. The main vertical pipe is just what you see, really: the T you see here where the drain goes into it is the only thing attached to it, otherwise it’s just a vertical pipe. Does that answer the questions or would you still like another photo? And it’s six-story building; YMMV on whether that’s “high-rise.” I’ll check building rules.
    – KRyan
    Commented Apr 22 at 21:10
  • Do you mean two dishwashers? And yes, it's helpful to know that past that Y are soft hoses, not rigid pipe so pressure against the trap is not coming from there. Look for photos of a typical under-sink plastic trap arrangement with integrated dishwasher attachment point.
    – jay613
    Commented Apr 22 at 21:14
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    @RMDman I suspect the contractors rather installed a new sink, and then tried to force the original 1942 plumbing to fit.
    – KRyan
    Commented Apr 22 at 21:52
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    The new photos help. I wanted to see if the stack of metal fittings and rubber couplings could be simplified. But I think it cannot. Go with isherwood's suggestion, except you may not need to replace the metal tee, just unscrew the metal trap arm and replace with PVC.
    – jay613
    Commented Apr 23 at 15:11

2 Answers 2

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The evident minimal approach if you're in some backwards jurisdiction that requires metal drain pipes (as approved by the city council, that has been well-bribed by the plumber's union, say) is a slightly shorter threaded nipple from the Tee to the Trap. Looks like it's otherwise lined up OK, just too long. A competent, properly equipped plumber could cut it shorter and rethread it for you. Usually it's less expensive to just buy a new one the correct length, though.

The modern approach is a much shorter threaded nipple and a sliding trap adapter (female.) That will need a new trap with a slip joint output (male), or an adapter I can't recall ever seeing from the female pipe threaded trap outlet to a male slip joint. These can be had in metal if your LAHJ requires it, but the polypropylene plastic versions last longer (they don't corrode.) The new trap would ideally be of the sort with a union joint in the middle of the trap that allows for an additional degree of freedom in meeting the sink output. The slip joint can be made shorter or longer, and the union joint can be rotated. Everything gets lined up nicely, and then you tighten the union nut and the slip joint nut.

If you have to replace that trap, be sure to take the old one to the scrap yard, not the dumpster. There's money in that bronze.

A hack job approach that may or may not meet local code would be to cut a section from the middle of the threaded nipple and join it with a rubber coupling (no new threads required) to make it shorter, and slightly adjustable. Since I see two shielded (stainless steel outside reinforcing) rubber couplings at the tee, that evidently either meets local code, or the hack job done to leave you with this mess was never inspected (it certainly should not have passed if it had been.) So you'd get a suitably sized shielded rubber coupling, take a hacksaw to the pipe, then saw it off again to make it shorter, file the cut ends to remove sharp edges, and join them with the rubber coupling.

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  • To be clear, by “nipple” you’re referring to the horizontal pipe between the trap and the black vertical pipe?
    – KRyan
    Commented Apr 23 at 15:10
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    Yes, the pipe that functions as a trap arm. A dual-threaded short metal pipe is unintuitively called a "nipple".
    – isherwood
    Commented Apr 23 at 15:38
  • Questioning that a female threaded trap adapter is harder to find than a male? I see both equally hard to find but available in copper, and neither in PVC at all, anywhere. Looking in detail at local plumbing supplier catalogs and manufacturer web sites. Am I wrong? I wouldn't add copper to this mix. If you can't find either, I'd replace the "nipple" with a male threaded PVC (not trap) adapter, a short piece of PVC pipe and a vanilla PVC trap adapter.
    – jay613
    Commented Apr 25 at 12:55
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The solution is almost always the same: Move the trap arm, often by the addition of an elbow near the stack.

I didn't read your entire tome, but I would be taking things apart back to the tee between the no-hub couplers in the stack. Then install a modern plastic trap adapter and a 45° elbow (downstream of the adapter). Get rid of all the cumbersome metal stuff.

From there, run a new plastic trap arm out and a new plastic trap with a swiveling joint. You now have virtually infinite alignment options. Everything can be perfectly straight.

See also Tailpiece not aligning with trap.

If you do want to keep the metal, you'll still do the same thing. Just get the trap arm off center a bit however it's easiest, then swivel the trap to align with the sink tailpiece. The rigid trap you have will make this a pain, though. Slip joints and swivel couplings are the bee's knees.

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  • Please bear with me; I wrote a tome because I don’t know much here and don’t know what’s relevant, and also have some questions about your answer. What does “the stack” include? When you say “things […] back to the tee,” can you specify exactly which section you mean? I think you mean the arm, trap, and tee itself, but I’m not sure. Also, which is the “adapter” here? Thanks so much.
    – KRyan
    Commented Apr 22 at 20:56
  • No worries. More information is better. "Stack" implies the vertical series of pipe and fittings. The trap adapter converts from the threaded or cemented stack to the slip-joint region of the trap assembly. The trap arm is between the trap and the adapter. The tailpiece is the vertical from the sink. Have a google for trap diagrams and see my answer on the linked post. I'm proposing that you eliminate all metal between the tailpiece and the stack tee.
    – isherwood
    Commented Apr 22 at 21:14
  • OK, I believe I follow that. The stack is the black vertical pipe, right? And I would leave that alone, and connect PVC to the existing T in the stack (between the two collars that say NSF)? So I replace the arm, trap, T, and adapter. If I don’t do that, I still need some additional piece to get the trap arm off-center, right? I don’t see any way the existing pieces could do it...
    – KRyan
    Commented Apr 22 at 21:48
  • You could connect to the tee, but it may be easier to replace it for simplification. See what your hardware store offers. Right. More pieces are needed regardless.
    – isherwood
    Commented Apr 22 at 23:18
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    @KRyan, I might be tempted to turn a blind eye to that and go ahead with plastic pipe as suggested in this answer anyway. It sounds like a code carve out to keep plumbers employed (because everyone who lives in a tall buildings are obviously rich, right? ;) ). If someone can explain how PVC in a drain under a sink on floor 6 is a risk to health and safety but not on floor 5, I'd be happy to reconsider...
    – spuck
    Commented Apr 23 at 20:12

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