This is the current situation...(this is a an old cask iron slop sink that came with the house.) metal sink, metal pipes, pvc ptrap There was a leak and we thought it was the p-trap...so we decided to get a PVC one. The other pipes are metal. After we connected the p-trap, there's still a leak...but I can't tell exactly where it is. It could be the metal pipe connection to the sink's drain. You can see that at the top with all the goop around it. I can actually jiggle that joint. (I wonder if it is threaded or they just added enough goop to make a connection (LOL).

Do I need to add thread sealant, pvc tape, etc to all the joints? You can wee that we added some to the joint that connects the p-trap to the wall pipe.

Can this setup work?

Can I use something like this to transition between PVC and metal pipe? Fernco adapter

Update I ordered a new free standing plastic utility sink and will attempt to connect that to the existing pipe in the wall

  • 2
    Based on the massive amount of caulk at the sink strainer and the fact that you can wiggle that joint, I'd venture to say that the down pipe there is on its last legs at best. I'd suggest that it may be worth the few extra bucks to replace the entire strainer/drain assembly with new. That way there's no worry about cleaning things up. I'd guess that when you get that caulk scraped away, you'll find a scary large hole. It'll only cost a few extra bucks and will be faster & easier than adding a bodge to an already bodged fix.
    – FreeMan
    Jan 13, 2023 at 12:51
  • 1
    If you're stuck with this setup, you need to do a better job tracking down the leak. Toilet paper is a good tool. Wrap it around the pipe below a joint, starting at the top just below the sink, and see if it gets wet. If not, keep moving the TP down the pipe(s) to the wall.
    – Huesmann
    Jan 13, 2023 at 15:53

3 Answers 3


I would dismantle completely that metal downpipe from the sink, clean all that crud off it, then reassemble using the jointing so it seals between the sink and the drain grille.

All that exterior sealer will always fail as the water has already got past the proper seal. Done properly it will not leak, assuming none of the components are cracked or damaged.

  • 1
    I would reassemble with a brand new sink strainer, drain and down pipe. There's obviously enough damage to the old metal one that it's time to retire it.
    – FreeMan
    Jan 13, 2023 at 13:32
  • The "savings" of the drain and down pipe in the last repair says a lot about the work done. I'm with you, if they couldn't spend the extra $20 to at least have one side of the joint be problem free, I'd worry about the other side too. And when doing it, get a proper PVC to iron pipe connector for the iron pipe.
    – Edwin Buck
    Jan 13, 2023 at 16:17
  • If I want to replace the enter sink with a new utility sink, can I connects PVC pipes to the straight pipe coming out of the wall (what would this connection piece be)? I want to try to do this work myself.
    – milesmeow
    Jan 13, 2023 at 19:14
  • I added details to my question after doing more research. Can I use a coupling with clamps at each end (like a Fernco adapter)?
    – milesmeow
    Jan 15, 2023 at 6:50

If this is a sink that gets daily use, (or even close to it), I would remove everything from the stub pipe coming out of the wall and replace everything with new parts. even a new drain basket. The old stuff probably has corrosion and pits which will make a headache trying to get it all not to leak. New plastic is cheep when compared to the hassle of fighting persistent leaks.


I would say that this is not a proper set up. There is no way to adjust the p-trap. One possibility for the leak is the pipes are not mating properly because there's no way to adjust them. Maybe it's an optical illusion but it looks like the downpipe is not straight and the nut looks like it may be cross threaded. If that nut is cross threaded it may seem like it's tight but that could be another possibility for the leak. As others have said replace everything. I'm not a fan of flexible pipes but unless everything lines up perfectly you may want to use a flexible tailpiece so you can get a little bit of adjustment.

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