Adding Sink to Existing Vent Pipe

[Korey Kashmer]

All, I just signed up here. I've hung around for years, getting advice periodically. I'm a pretty big DIY person and tackle many things myself. I do use contractors when the need arises.

I'm currently finishing my basement and need some minor plumbing work done. I've actually had 2 different licensed plumbers come in and give quotes, both had completely different takes on this seemingly simple work. I figured I would ask this community!

I need to plumb up water and a drain for a wet bar sink. Fortunately, the location is right next to where the vent stack is and plumbing for the bathroom on the other side.

My need is to tie in a new drain line with a distance of roughly only 12" - 18" to an existing 2 inch vent stack that already supports the kitchen drain and will eventually support the bathroom fixtures. ((See attached photo for clarity.)) You can see where I drew in the new drain line.

1 plumber quoted simply tying the line directly into the existing stack, directly between the bathroom sink 1.5 inch line and the kitchen drain line. (Simple enough)

the second plumber said adding the drain line there would be against code, and they would need to bust up the concrete and tie the line in lower down. I asked why, and he basically didn't say. He just said, it probably wouldnt pass code.

My question was, is the code that tie ins have to be so many inches apart? I couldn't find anything on that. a 2inch line seems to support quite a few fixtures, well less than what I am seeing. And, that wasn't his issue anyway. It was where the tie in would take place. He mentioned something about gurgling.

Any advice would be great. Interesting how to licensed plumbers have completely different takes.

 

[Terry]

A bathroom group can vent with a 2" line. That takes care of the toilet, tub and lav.
Also, you can't have a fixture on the second floor be part of a lower floor wet vent.
Same floor, bathroom fixtures only.

The kitchen sink and bar sink can't be part of a wet vent, but should come in downstream, or go back and add venting.
If the only vent you have there is the 2" I see, it's already wrong.

When a kitchen sink is drained, that's a lot of water at one time.

 

[Sponsor]

 

[Korey Kashmer]

Terry, thanks for your quick reply!

So this is a new construction home and it did pass inspection. I know that probably doesn't mean to much.

I will add, the kitchen sink coming down, does have a vent under the sink. It's one of those cap type vents, not a direct pipe vent. With that, does that mean it's actually piped right then (without the bar sink)?

 

[Terry]

Is there a separate vent for the toilet?

 

[Korey Kashmer]

It doesn't appear to have one. For more context, this is in our basement. The toilet and shower drain pipe are in concrete. They flow to a grinder pump 3 to 4 feet away. That takes the liquid back up to the main sewer line out of the house.

The sink from the kitchen is on the main floor, with the drain pipe basically coming down and tapping right into the drain lines for that bathroom. (in picture). Outside of the bathroom, the kitchen sink is the only other appliance on that drain line right now. Multiple plumbers have said it was weird they set it up that way. They might not have been able to get the fall they needed to run the kitchen drain all the way to the back of the house, not real sure.

 

[Terry]

The kitchen drains into the vent line for that bathroom. That is not correct in any plumbing code.

The sewage ejector (grinder) should also have a vent through the roof.

I like the guy best that knows that the floor needs to be opened up.

 

[Korey Kashmer]

The grinder does indeed have a vent pipe. So I need to get our inspector involved then in regards to how the kitchen is piped right now. I assume they will have to re-run the kitchen drain straight to the main drain out.

Terry, with all this said, if they re-route the kitchen correctly, then can a wet bar sink be added to the bathroom drain system with that vent? And if not, how should that be tied in then? I believe you mentioned down stream. I assume that means ripping up the concrete then and tying it in below all the other stuff.

I guess that's where my hang up is. Why would it matter if it's directly below the bathroom drain (wet bar drain) or further down underground.

Thanks again for your help! I'm learning things are not right currently lol.

 

[Terry]

By code you can't have the bar sink in the bathroom group wet vent, but really, it's pretty much a lav as far as function.
I've never understood why a bar sink doesn't get included, other than it just wasn't discussed to be added to it.
The drain on a bar sink is pretty tiny.