What is this drain line for?

[Fusion916]

I have a drain line that sticks straight up in the air and goes down into the basement on the side of the house and into the city drain/sewer.

Anybody have a clue why this is there?

 

[johnjh2o]

Looks like a vent to me.

 

[Fusion916]

Looks like a vent to me.

Vent for the city sewer line? Does that make any sense?

 

[johnjh2o]

It's hard to say without seeing where it's connected. I could be a vent for a house trap.

 

[Fusion916]

It's hard to say without seeing where it's connected. I could be a vent for a house trap.

It's connected here to the picture I've previously posted:

 

[johnjh2o]

There at one time was a fixture there and the line you're referring to was a vent for that fixture.

 

[Fusion916]

There at one time was a fixture there and the line you're referring to was a vent for that fixture.

Sorry again I'm new to plumbing but I am confused

If this was just a vent for some fixture that was apparently in the basement, why connect this to the city sewer at all? Why not directly outside?

 

[AQualityPlumber]

I don't see a 2" vent connection that you took a picture of. You have a back water valve installed.

 

[Fusion916]

I don't see a 2" vent connection that you took a picture of. You have a back water valve installed.

The pipe I am referring to is in the OP where it goes straight up along the house, the previous picture I posted was that same pipe going into the basement and is connected to the drain line. And yes, it's connected through the backwater valve, which I don't understand.

 

[johnjh2o]

You have a capped line there that at one time connected to something that was vented with the line running up the outside of the building.

 

[Fusion916]

You have a capped line there that at one time connected to something that was vented with the line running up the outside of the building.

Understood, but what I am confused about is why it was every connected to the drain line.

Oh well, I'm going to remove that piping then.