Santa Cruz, CA, USA

I think this question might be related to Under bathroom sink piping (exposed) but my question is more general so I decided to post it separately.

I'm in the middle of a bathroom remodel and getting ready to buy/build/connect parts for a sink drain assembly. Things are in the early stages so I don't have precise measurements of the vanity yet. What I'm wanting to know is:

  • Generally speaking, what should the recommended shape of drain pipe be?
  • If a "P" trap is recommended, where should it be located in relation to the height drain outlet on the wall?
  • Aside from a "P" trap, is there any other specific drain pieces that are recommended?

Here's a picture of the wall (outlet pipe is a 1.5 inch iron pipe).

wall where drain is

  • 2
    Straight out into the P and then straight up. Same with a U trap. Dec 20, 2014 at 22:58

2 Answers 2


You should be able to find a P-trap assembly available at any local hardware store.

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The horizontal section should attach directly to the drain line coming out of the wall, while the vertical end should accept the tail piece from the sink.

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Sink needs to be above the drain and the trap need to fit between to sink and drain. Since the trap keeps sewer gases from entering your house through to drain, they are very important.

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