Question: is there a gasket or anything like that that goes in the joint on the outlet of the ptrap? See pic, you know,the short side that goes to the sewer drain through a connector pipe. Darn if every internet diagram Ive seen shows one but nothing fits and thats where my only leak is. The joint from the pipe to the ptrap looks like it should fit together without any gasket at all. I should be able to just tighten the plastic nut,right? Maybe I'm not tightening enough? BTW, the sink right next to it doesn't leak and there's no gasket there! Any wisdom?

It does not need a gasket. The bevelled ends of the trap and the trap arm mate and seal without a gasket. It does not need a lot of tightening of the nut to achieve the seal on PVC pipes.

Damage to one of the bevels can cause a leak. The trap and the trap arm come as a pair. Mixing and matching from different manufacturers can lead to improper mating.

As a last resort, before replacing the pair with a new one, you can try a light coating of silicone on the mating surfaces.

Post a picture of the trap arm end that mates with the trap outlet.

if the outlet side is flat with a ridge in the center, then it needs a gasket.

if the outlet side is beveled upwards than it does not.

You guys are awesome,I'm getting a new ptrap!



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Well,I got a brand spanking new ptrap kit and installed it...tightened all connections hand tight...IT STILL LEAKS!
I've got a theory: (maybe a crackpot theory. I'm sure someone will tell me!)
This bathroom was first constructed in '91. I think the plumbers MAY have violated some plumbing rule.(like not having two ptraps on one drain line. I think I read that somewhere. someone can set me straight if it's not true) I don't feel like ripping out the wall to verify that

George from Canada, didn't you mention silicone to seal the joint?

Ken the non plumber



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no, never use silicone caulk to seal a trap slip joint. use silicone grease to make it tighten easier and better.
remenber you will need to take the joint sometime in the future



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Did you try to tighten the nuts a little more with a wrench? Two traps won't cause a leak. Where is the leak coming from? Is there a gasket required at the leaking connection? Pictures available?



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Post a picture of the p-trap assembled and indicate where the leak is.

Any chance you are mixing 1-1/2 and 1-1/4 tubular parts and not using a 1-2/2x1-1/4 washer where you have a size change?



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You can also try wrapping the threads with Teflon tape to help seal/lubricate then put it together.



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No gaskets required on that joint (outlet of ptrap) and no I'm not mixing up sizes,everything is 1 1/2. The leak is on top of the slip nut so anything I put on the threads (like tape won't help) Think I'll try tightening some more.

Ken the non plumber



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is there an alignment issue? Do you have to push together the parts to engage the slip joint? Try loosening all the slip joints from the tailpiece of the sink to the wall, then align all the pieces and incrementally tighten all the parts at the same time to make sure all are aligned and not one joint is taking any strain.



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Alignment looks ok.Notice how close the valves are,makes it tough to tighten the slip nut in question.

Close the valves, remove the sink hoses, you should have enough space to get in there. Several types of wrenches existo to help tighten that large nut in tight spaces, here's the one I use:

[www.plumbingsupply.com]

Hey Dave from CA, that"strap wrench" is what I need. I'm going to get one,I'll post how it works out.

Ken the non plumber

Are you using the stiff nylon cone washer or the more rubbery usually red colored cone washer?

just shut off the cold and remove bottom compression joint. you'll have plenty of room for a wrench

Well,I DID get a strap wrench and I WAS able to get it in there amongst the obstacles but because of the "ears" on the slipnut,it couldn't grab so my wife and I went back to trying to tighten the nut using a screwdriver up against one of those "ears" and hitting the screwdriver with a hammer. That seemed to tighten it enough so we've not seen. any leaks.

Ken the non plumber

I'm no plumber of course but I HAVE learned a few things about sink drains while chasing this leak. Maybe it'll help someone else: That connection (on the outlet of the ptrap) is the only connection in the sink drain that's constantly under water.Hence that's where a leak is likely to show up. It's always under water because the water level has to be well above the p trap to insure that no sewer gas can possibly get by into the bathroom. THAT connection should be tightened well unlike the others that can be hand tight. I didn't find anywhere on the WEB that actually explained this. I had to look carefully at many diagrams!
Like I said, I hope this helps someone.

Ken the non plumber

My guess is at the time the plumbing rough in was done it was for a pedestal sink and both supply valves need to be hidden behind the pedestal hence why they are so close together.

Imagine the person who had to replace the p-trap with the pedestal in the way, and having to tighten the drain nut with the pedestal in the front, supply valves to the sides, and the tightening had to be done with a hand reaching back around the pedestal.

I get the feeling that the OP's leak was always at the trap outlet, not at the inlet with the slip nut. Halfway through we switched to advising him on how to stop a inlet leak.