How can I reattach a drain pipe that detached under the sink?

Question

Recently, I had a clog in my bathroom sink that I wanted to attempt to fix myself. Believing the clog to be in the P-trap, I bought a pipe wrench, removed the trap, cleaned it out, and attempted to fit it back onto the sink (side note: the clog was actually at the top of the drain, which I later discovered; who knew?). However, when I attempted to reattach it, the pipe that drops down from the base of the sink came detached — it appears that it was only held on by some kind of seal between it and a rubber washer. Now, when I run water, it leaks out of the base of the sink (and also the top end of the P-trap, but I may not have tightened that enough).

How should I go about reattaching it? Is it as simple as getting some kind of putty to fix the seal, or am I maybe not aligning the P-trap correctly?

Edit: I thought an illustration of the problem might be helpful: https://vimeo.com/68243871

Answer 1

It appears from the video the sink bottom connection is assembled wrong. From top to bottom you should have sink, rubber gasket, metal flat washer, brass nut. This or the P-trap connection do not need to be super tight, firmly snug should be enough. If the connections leak when snug, the gasket or sealing ring is likely damaged, or possibly their mating surfaces are not clean and smooth.

More disturbing is you say drain/popup detached from the sink when you were fussing with the P-trap? This should not be possible. If it did happen, the drain/popup is broken and needs to be replaced. This is not something you could have done alone, it was ready to break anyway. The flange you see when standing over the sink is part of this assembly, the large nut underneath sort of clamps the sink between the rubber gasket and this flange. The drain/popup is normally installed by dropping it in from above. If it came out from the bottom it is broken.

Answer 2

The tailpiece is connected to the base of the drain-popup with a fine pitch thread. You can use Teflon tape or pipe thread sealant. Sometimes there is a tailpiece extension that attaches as you describe: a jamb nut and a plastic (sometime rubber) bushing. The bushing must fit tightly (and the pipe must be smooth and clean) around the pipe and make a compression connection with the top of the extension. The lower end of the extension has another nut-bushing pair where it connects to the inlet of the trap.