A vertical drain tube that separates from the sink fitting usually points to a loose slip joint, failed washer, poor alignment, or insufficient insertion.
Why this matters
The connection seals by compressing a tapered washer around the tube. The nut does not glue the pipe together, and tightening cannot compensate for a misaligned or cracked assembly.
Tools and materials
- Bucket and towels
- Slip-joint pliers
- Correct-size slip nut and tapered washer
- Replacement tailpiece or extension if damaged or too short
What I found and what I would do next
- Stop using the sink. Place a bucket below the open connection and dry the cabinet so new leakage is obvious.
- Back the nut off. Slide the nut and washer onto the loose pipe in the correct order; the tapered face normally points into the receiving fitting.
- Check alignment and reach. The tube should enter squarely with enough overlap that movement cannot pull it free.
- Inspect the washer. Replace a flattened, split, hardened, or missing washer. Do not try to seal a damaged washer with tape.
- Seat and tighten. Push the tube into position, hand-tighten the nut, then use only a small additional turn if needed.
- Test in stages. Run a small amount of water, then fill and release the basin while watching the joint.
- Dry the cabinet structure. If the cabinet bottom has swollen or delaminated, stop the leak first, dry thoroughly, and evaluate a fitted overlay or panel replacement.
Common mistakes
- Putting thread tape on slip-joint threads
- Installing the tapered washer backward
- Forcing misaligned pipe into place
- Replacing cabinet wood before the leak is proven fixed
Know your limits
Call a plumber when the drain cannot align without stress, the metal drain body is corroded, the wall connection moves, or hidden cabinet/floor damage remains wet.
Start with the diagnosis. Work safely, use the current product label or manufacturer instructions, and stop when the project moves beyond your tools, experience, or comfort level.