I recently bought into a new place. It's a fixer-upper, but before my wife and I start the work, we're living in it while we finalize our plans.

Our kitchen sink does not drain on its own. We either need to use a plunger to get airflow going or squeeze the pipe a couple of times (it's flexible rubber; which I've never seen before) to get it to drain. We declogged it with a liquid product a couple of times, and once we get airflow, it drains fine.

I was looking under it, and noticed that the sink drain and the waste outlet in the wall is at the same height, with a P trap between them.

Would this (lack of) height differential be preventing the sink from draining?

If so, what would be our options? We plan on moving the kitchen when we renovate but until then, we're kind of tired of water piling up in the sink.

1 Answer 1


air admittance vent

Try to add one of these to allow air into the drain

  • Thanks for the tip! I'll run to the hardware store and see what I can find. Dec 29, 2017 at 15:15
  • @BelgoGringo In that illustration it shows the air admittance valve as being BELOW the height of the sink drain. I was under the impression that a air admittance valve needs to be above the level of at least the drain if not the top of the sink. While the image does include the manufactures instructions on height i am Not sure it meets code. ?
    – Alaska Man
    Apr 21, 2018 at 16:43
  • @Alaskaman yes I always go as high as I can under the countertop.
    – Kris
    Apr 21, 2018 at 19:55
  • Certain types of valves are in code and others are not, depending on where you live. Make sure to use the ones rated for indoor remodels, NOT the ones for RV venting.
    – Zediiiii
    Oct 10, 2019 at 18:20

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