I'm remodeling my basement which includes a bar. I want to add a sink to the design but I'm not sure I'm able to drain it. I have a drain stack right next to the location where the sink would go. That drain stack comes from the upstairs utilities (two full baths). Can I cut into that line and add a Y-junction to drain the bar sink? I can send pictures of what the stack looks like if that would help.

You can add a Wye remembering to have the wye angle down obviously. You need to trap that sink and if there is no vent available you might be able to use an air admiitence valve (AAV) if your code allows.

Hey Joe:

Sounds like you can connect into the stack using a wye fitting... but be clear that the drain to sink will require a vent to be connected within 3-5 feet or so of sink ptrap, and that vent will need to be run to upstairs vent either at upstairs bathroom or all the way up to attic.

If no vent trap for sink will siphon and sewer gasses will be unbearable!

YOU MAY be able to install a mechanical vent if allowed in your area (see pic.). It is an aav (air admittance valve) that allows air into drain line when using the fixture and when water from upstairs baths rushes by (so will not siphon the trap). This may be an alternative, but need to see if allowed in your area (call local plumbing inspector's office and ask him).

That is what I have for you now... anything you think I missed or misunderstood.. Let me know... Mark

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Funny Bob... basically said the same thing... who needs me around here anymore... ;)

Hey Mark, I beat you by 6 minutes because you type slower than I do. Where did the pic disappear to?

I do type slowly... but getting better everyday... ;)

Pic. Is there now... think I forgot to post. Thank you for pointing it out!

So, if the stack in question goes up to the second story utilities and its vented upstairs, do I still need to put a vent in for that sink? I'm still pretty green when it comes to plumbing, but I'm assuming the gases take the path of least resistance and seeing the pipe for the sink is in the basement, that's the place it will travel to.

If I still need a vent there, can I run it up the wall to just above the foundation and run it outside (similar to how you would run an exhaust of a direct vent furnace)?

If I still need a vent there, can I run it up the wall to just above the foundation and run it outside (similar to how you would run an exhaust of a direct vent furnace)?
Hey Joe, Yes you may, but you must get approval from the plumbing inspector and you may not terimate it beneath any, door, window, or any ventalation opening, nor shall any vent terminal be within 10 feet horizontally of such a opening unless it's at least 2 feet above suck opening. The vent terminal shall be located no closer then 10 feetfrom any lot line and shall be turned up and screened. Vent terninals also shall not terminate under the overhang of a building. Hope this helps. Tom

Hey Joe, I think that you have a slightly off idea about the vents purpose. While it does allow sewer gas to vent to the roof line it also allows air to get sucked into the drain line to displace what the water pushed out. Without a vent or AAV for that sink it will chug and gurgle and not drain well. Check with that inspector to see if an AAV is allowed, looks like your esaiest, cheapest option to me.