Can Someone Explain this Extra Sink Drain

[Skoby]

The drain on the left was used for my kitchen sink. The drain to the right was capped off when I moved in.

I'm not sure why the drain to the right is there. I was going to cap it off in the wall.

I'm assuming the pipe coming up from the floor is a vent for downstairs plumbing so I should leave that?

I'm curious what the drain on the right could have been for. I'm not a plumber so I wanted to ask here. Thanks

 

[Treeman]

Is there any chance that they ran a dishwasher into a separate drain as shown in this pic below:

 

[Sponsor]

 

[Terry]

I've been roughing kitchen sinks in at 16" to keep up with the new 10" deep kitchen sinks.
The drain on the right might have been for a dishwasher. You can cap that and use the disposer for a drain if you like.

 

[Skoby]

I'm on a septic tank so I don't run a disposer. I don't run a dishwasher either because I live alone and would rarely use it.


If I run a dishwasher in the future can I just run a tailpiece under the sink or do I need an air gap installed also? I didn't have an air gap in my old residence, I didn't know they were needed.

 

[Terry]

You can run a tee from below the sink basket.
The reason they have an air gap is to prevent water from draining back to your dishwasher. Some dishwashers have a high loop built in, and some don't. I've seen dishwashers fill with murky water between uses, really smelly water. This was cured by using an air-gap on the drain.

 

[Plumber69]

It's a clean out plug. usually not plumbed that way

 

[Skoby]

Alright, cap it and make sure I use an air gap if/when a dishwasher is installed. Thanks guys