In CA, would code allow for a drain line to be tied into the vent line shown at the location of the red arrow below?

Single family home.

Happy to draw a picture of where that vent lines goes, if that makes a difference.

enter image description here


  • are you wanting to put another drain in the island, or does the vent pipe just conveniently happen to be where you want to add a drain?
    – longneck
    Commented Oct 2, 2015 at 20:41
  • 2
    Not likely. The vent is there to provide air to the island sink drain, draining through the vent compromises that.
    – Tester101
    Commented Oct 2, 2015 at 23:17
  • the vent pipe just conveniently happens to be where i want to add a drain
    – tom
    Commented Oct 3, 2015 at 0:21

1 Answer 1


No, you can't add a new drain to the vent stack. That would compromise the function of the vent.

To add another drain in to your plumbing system, you have to make sure that the waste line and vent are large enough for the fixture.

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