Bathroom Drain Vent


Old 11-23-19, 10:34 AM
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Bathroom Drain Vent

I am working on rough in for my basement bathroom. Most of the work is done by builder except water distribution between sink, toilet and shower which I am planning to use PEX pipe and sharkbite push connector. My question is about drainage.
I see builder has drainage system built under ground for toilet, shower and there's also one 2" pipe for sink too which all goes to Pump in other part of the basement which has vent and drainage. All looks good, but I got CONFUSED with one more 2" pipe coming from top of basement ceiling and looks its another vent pipe. I am wondering if I need to use that. If I used it then I will be able to use it for sink only. Shower and Toilet goes under ground to pump and I don't see any way to connect that vent to toilet and shower. Any suggestion?
Old 11-23-19, 03:36 PM
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You have to identify what each pipe does. We can't see what you have so we can't say for certain if that 2" pipe is a vent.
Old 11-24-19, 08:17 PM
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Thank you for response. Please see the image below. There are 3 drain pipe out from ground going to Pump and there also 2" pit from ceiling that I assume is vent going out to roof via bathroom above on upper level. Is there a way to find if the 2" pipe is vent or not?

Old 11-25-19, 04:04 AM
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I can think of a couple things.

Call the builder.

Look at the roof to see if there is a 2 inch pipe exiting in the upstairs bathroom location.
If yes then uncap the pipe and look up. If you see sky then it is a vent.
At least it looks like it is capped but I am not sure why they would cap a vent.
Odds are that it will not go straight up but you can never tell.

You could uncap it,
Tape a compressor hose to it and seal as best you can,
Turn the compressor on.
Then have someone on the roof checking the vents for the air escaping.
A leaf blower may also work.

Another possibility is that it is for central vacuum.
If you have it then uncap it and turn the vacuum to check.

Last edited by manden; 11-25-19 at 05:16 AM.
Old 11-25-19, 11:03 AM
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The 3" pipe is the toilet.
The 2" pipe next to the toilet is for the vanity, following up to the roof vent.
The 2" pipe to the right in your pic is most likely for a shower (or tub).

From the layout, it looks like the bathroom was originally designed to have a wall perpendicular to the wall that's built there now. So the vanity sink would be to the right of the toilet. You should be able to redirect the sink over to the right in that wall since you used 2x6" studs.
Old 11-28-19, 04:02 PM
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Thanks for response, I found out that pipe from ceiling is vent and needs to be connected to the with sink drain.

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