PVC tubing leaks

Hello,
I've just replaced my old corroded and leaking cast-iron pipes under my kitchen sink in my 100 year-old home with new PVC tubing. For the most part, things have worked out well.

However, I have a consistent leak where my tubing enters the horizontal drain pipe in the wall. I've tightened the slip nut; i've applied a little bit of teflon paste to the washer; i've ensured the the pipes are properly aligned (my pvc tube feeds ~4" into the drain pipe; but I cannot stop this leak. It only occurs when I run a leak test and dump a sink-full of water through at once, not during regular running.

What can I do to stop this leak? I suspect the issue is the low-quality poly washers that are included in the pvc tubing kits; but they seem to be working elsewhere in the system I'm not totally sure on that. I've got very little plumbing (read: none) experience so any input is helpful!

Thanks!
Manzell B

If the pipe is cocked, it can leak. Are you sure you have the bevel going the right way? It needs to face away from the nut so you are driving the bevel into the fitting, not under the nut.

If you have to use two washers or plumbers's putty. You've got a surprise coming in the future.

You obviously don't have it fit correctly. Redo it before you flood your cabinets. You may have the fittings cross threaded. Hand tighting it will be fine. Ditto on the tapered portion that gets pushed into the pipe.

If you have steel piping in the wall (it wasn't clear just how much you replaced) then make sure that there is no corrosion on the inside of the pipe where the slip washer will seat. Anything that keeps the slip washer from making a perfect seal, including a rough edge on the pipe, will create a leak point.

You may have a hairline crack in the nut from overtightening. Also, if the pipe coming out of the wall is galvanized MIP, a deeper plastic nut with FIP threads often produces a better seal than the standard slip nuts that come with p-traps.

leak

Does the slip nut screw directly onto the pipe? If so, that is the problem. You need a device called a Marvel connector/trap adapter/DeSanko, or any of several other names for it. That screws onto the pipe, then the slip nut screws to it. It has a taper to receive the washer, which a plain pipe does not.

Hello everyone,

Just so everyone knows what I started with:



These pipes had become very clogged (and smelly) over the years. I was initially concerned with the slow draining, so I poured a popular drain fixer down the pipes.

The next morning I had a large brown puddle in front of my kitchen sink. Here's why:



It's unclear if the pipes were about to corrode through or the highly toxic pipe cleaners did the trick. Either way, the pipes needed to go.

I decided to replace all the pipes as well as the odd baskets that were installed.

I found plumbers putty was much better than silicone at securing the baskets in place and not leaking around the basket (i learned the hard way). I would recommend that if the ability to take everything apart is important to you (as i had no experience, this was important) then you shouldn't use silicone sealant anywhere in the project.

You'll notice in the old pipes the drain line runs horizontal below each drain. I suspected that this made it easier for water to back up into the opposite sink, which had also been a problem.

Anyway, i fitted together new PVC tubing and screwed it all together. It was very easy.



As I mentioned before, I had a problem leak where the PVC went into the existing steel pipe. You can't see it in the picture, but I ended up using the old poly slip washer and metal slip nut to make the last threaded connection. This worked like a charm! I cleaned out the inside of the pipe as well, so that probably helped make a better seal, but I felt the metal nut allowed me to tighten a bit better.

Anyhow, thank you all very much! I could not have done this project without help from you and all the information on the net!

- Manzell B

Looks good. But if it starts to leak again, take HJ's advice and buy a trap adapter.

In all the years Ihave been doing pluming I have never seen any thing like
this trap adapter is way to gur house was built 1869.
I feelyour pain.