Recently replaced the kitchen sink in our RV, and having a hard time figuring out how to join the drain into the existing PVC drain pipe.

It was original a dual sink, which might be why the main drain pipe is 2". The existing P trap is where it goes from 2" down to 1.5" for the drain, but it no longer lines up, and I'd rather not have to use flexible drain hose. Is there an easier way to go from 2 inch threaded PVC down to a 1.5inch pipe that we can then use a regular slip joint P trap on? enter image description here

  • Picture makes it appear that the new sink comes out too low to properly drain downhill into the drain pipe. Is that an optical illusion?
    – Ecnerwal
    Mar 12, 2023 at 21:57
  • It's definitely closer than I'd like, but the bottom of the sink basin is about an inch above the top of the drain pipe. That should be enough, right?
    – jrp07f
    Mar 12, 2023 at 22:10
  • please mark a spot on the black pipe that is level with the bottom edge of the sink downpipe nut (the nut you would loosen to remove the dowmpipe)
    – jsotola
    Mar 12, 2023 at 23:14
  • Can you replace the drain tailpiece with a shorter one?
    – Huesmann
    Mar 13, 2023 at 12:37
  • @Huesmann Tailpieces can be cut. They only come in a few sizes, and you shorten longer ones to get the actual size you need.
    – Ecnerwal
    Mar 13, 2023 at 13:19

1 Answer 1


Sure. A trap adapter, which you can get in PVC-glue or threaded flavors for the end that connects to the drain. The other end is a standard slip joint, often including a washer seal for both 1-1/4 and 1-1/2 sizes.

Or if what you really want is 1.5" pipe, simply a reducer. But you can stay 2" up to the trap adapter (decreases the odds of a clog...)

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