How do I fix a broken copper-to-plastic connection under my sink?

That copper piece snapping is a classic case of corrosion finally giving up the ghost. When you have old thin-wall copper meeting plastic, the metal eventually turns into paper-thin foil from the inside out, and any torque from a wrench will just shear it right off. You defintely want to ditch the metal entirely and switch to a full plastic assembly for the kitchen sink.

Go to the hardware store and pick up a **plastic dishwasher tailpiece**. It is a specific type of pipe that has a small branch coming off the side for your dishwasher drain hose to clamp onto. Since you mentioned the area is crowded, this is actualy going to save you space becuase you can orient that branch in whatever direction gives the hose the most room. You'll also want a new 1-1/2 inch slip-joint nut and a beveled poly washer to connect it back to the P-trap.

When you are putting the new plastic pieces together, remember that they are designed to seal through the compression of that poly washer, not by cranking on the threads. You only need to go **hand-tight** plus maybe an extra eighth of a turn with pliers. If you over-tighten plastic, you risk distorting the washer or cracking the nut, wich just leads to more leaks down the line.

If the vertical distance between your sink basket and the wall drain has changed, you might need an extension tube or you might need to trim the new tailpiece down with a hacksaw. Just make sure the beveled side of the plastic washer is pointing toward the joint it's sliding into. If you flip that washer the wrong way, it won't matter how tight you make it; it’s going to drip. Once it's all cinched up, run the water and the dishwasher to check for leaks under pressure.

I had this exact mess last year. Since you're swapping to plastic, grab a flanged tailpiece washer for that top connection where it hits the sink basket. Kits ussually come with beveled washers for the bottom, but they often skip the flat one for the top. If that old one is gunked up or missing, it’ll leak from the top down. To deal with those crowded hoses, I used a stainless steel worm-gear clamp instead of the factory spring clip. It let me cinch the dishwasher hose tight against the back wall so I coud actualy fit my cleaning supplies under there again. Just snug it down with a screwdriver.

While switching to poly is definitely the move, you must ensure your vertical alignment is absolutely plumb because even a slight angular deviation will cause that beveled washer to seat unevenly, wich inevitably leads to those slow, weeping leaks that ruin cabinet floors. I’ve found that many people forget to deburr the inside of the plastic pipe after trimming it with a hacksaw, which creates a snag point for debris that eventually causes a stubborn clog right at the dishwasher inlet junction. If you're struggling for space with the hoses, you might also consider rotating the entire P-trap assembly on the wall-side waste arm to give the new branch more clearance.

Since you're tearing it all out, don't bother salvaging the old P-trap. Grab a **Dearborn P9703BG** 1-1/2 inch polypropylene kit. It’s got a reversible J-bend wich is a lifesaver when your wall drain height is a bit wonky or the alignment is slightly off.

Also, keep some **Oatey Great White** pipe joint compound on hand—just a dab on the face of those poly washers helps them seat perfectly without having to crank the nuts. If your basket strainer looks as crusty as that copper was, swap it now for a **Kohler K-8801-CP** so you don't have to crawl back under there in six months when the old putty seal finally gives out.

Quick update—I grabbed that Dearborn kit and switching to poly made things way easier. That reversible J-bend was a lifesaver for my wonky wall drain. I’m still having a hard time getting the dishwasher line to sit right without crowding the new pipe, though. Is there a specific bracket or clip you guys use to keep that hose tucked out of the way?