I'm installing a wet bar sink in the basement and would like to tie into the drain (2”) that services the kitchen sink upstairs. It is about 5’ for the drain and I have no way to dry vent. Is it OK to use this drain as a wet vent and do I need to plumb the bar with a 2” drain because of the distance that I’m from this drain.

We are not allowed to wet vent on a kitchen sink drain in our area. As far as lengths of trap arm( or dirty arm), 1 1/2 is good for up to only 3 1/2 feet, 2" is good for up to 5 feet(with correct slope). So yes you should go with two inch. Is there any possability at all to dry vent the fixture trap?

It would be very difficult to do unless I punched a hole out the side of the house and I don't want to do that.

As suggested by Mygirlsdad, you can't use a kitchen sink as a wet vent. If you do, you can be sure that the trap from the bar sink will siphon and gurgle and sewer gasses will enter the home... *YUCK*.

If you simply can't run a dedicated individual vent for the bar sink then, although not CODE LEGAL you could install a mechanical vent... called an AAV (air admittance valve)... see pictures. These are sold at all home improvement stores and should work nicely for this situation.

Here, you can connect into the 2" kitchen sink drain but you will install the AAV near the trap as indicated in the last two pics.

Let us know what you think.

MARK

It looks like using a mechanical vent would be the thing for me to do. I was thinking that wet venting could cause a vacuum and suck the trap dry, but I wasn't sure. Also I was thinking as long as I was not wet venting with a toilet and along with the larger pipe diameter it was OK.
I'm not getting a permit for this and as long as I don't stink up the house and the sink will drain, this works for me.
One more thing;
Does anyone know if a AAV meets code in Washington State?

Does anyone know if a AAV meets code in Washington State?
Washington State falls under the UPC Plumbing Code.
Milo or some of the other West Coast plumbers might be more up to date then I but Under the Uniform Plumbing Code (UPC) ALL VENTS must terminate through the roof, however the UPC will allow a maximum of one AAV per structure, however, The UPC only allows a maximum of one AAV per structure with the expressed consent of the local inspector
Based upon information presented in the original post this homeowner is under the UPC, and while it is legal to use the AAV it is understood that this is the only one that may be used in the structure.
Hope this answers your question. Good luck with your bar sink. Tom

Thanks for all your help.

Let us know if you need more. Cheers, Tom