My toilet, sink, and tub are all tied in to a cast iron Wye, and my sink is not vented so I want to re arrange the plumbing. Would this setup be up to code using a left and right side inlets facing each other and the toilet draining in the middle. I read somewhere you could not have to waste lines facing each other. The main waste lines are 4 inches and the sink and tub would be 2 inches coming in to the San Tee fitting with the left and right inlets. Plumbing setup

Here is the link for the Sanitary tee I will be using.


  • What is the applicable plumbing code of your local authority having jurisdiction? (LAHJ) - that weeds out all but one of the places to "read things somewhere" and gets to an actual answer faster... Also may matter how far from the toilet to this tee entry?
    – Ecnerwal
    Commented Mar 13 at 23:52
  • If I understand correctly, the distance of stuff to the vent/drain matters if you need a separate vent or an extra pipe to the vent stack. From the diagram you might want/need to change the wye.
    – crip659
    Commented Mar 14 at 0:05
  • I am in MA they follow the UPC but it does not clarify on using a that specific tee that Home Depot sells. The tee is right behind the toilet. So it is 15 inches from the center of the toilet flange.
    – Jrivers
    Commented Mar 14 at 0:08
  • Is the toilet some kind of wall mount type?
    – Huesmann
    Commented Mar 14 at 12:28
  • No the toilet flange will be 12.5 off the finished wall.
    – Jrivers
    Commented Mar 14 at 14:25

1 Answer 1


Yes, that is what the tee is made for. There can be issues with two drains facing each other, especially if they are toilets or other fixtures with a high flow. A simpler arrangement would be to use a single-side right outlet tee and connect the sink above. This would create a wet vent between the sink and the toilet. See the below sketch where the left sketch is your configuration and the right sketch is the wet vent configuration. enter image description here

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