Wye pipe placement for upflush toilet

[ctdames]

Hey! I’m a Jack of all trades but I’ll admit I’m not the most confident when it comes to plumbing. I’m installing a half bath in my basement with an upflush toilet. I’m wondering where the best place is to insert my wye (see pictures). I’m also curious as to what purpose the already installed Wye has. Thanks!

 

[MicEd69]

Need just a little more information to answer your questions.

What drains in what lines? Where is your main sewer? Are you on a city or septic system? etc.

 

[ctdames]

I’m assuming the kitchen and and second floor toilet drains into those lines. I have no idea what purpose that wye in the picture serves. It just branches off on its own and goes into concrete - right next to the other drain. The main sewer is across the room in the finished area of the basement. It’s drywall ceiling so would not be easy to get over there. I’m on city water - house built in 2007.

 

[breplum]

Those large white pvc pipes are not DWV plumbing pipes. We don’t have Radon out here but, I suspect that is what those pipes are for.

 

[ctdames]

Those large white pvc pipes are not DWV plumbing pipes. We don’t have Radon out here but, I suspect that is what those pipes are for.

Yeah you are right. The only other place is the main sewer line across the room. Extremely difficult to get to.

 

[breplum]

Point of fact. Tee fittings (like your photos show) are not allowed by any code to be used for waste piping in when transitioning from vertical to horizontal.
You might extend the cleanout so as to add a wye for your proposed drain.

 

[MicEd69]

Point of fact. Tee fittings (like your photos show) are not allowed by any code to be used for waste piping in when transitioning from vertical to horizontal.
You might extend the cleanout so as to add a wye for your proposed drain.

MrInfoPhilly and I had a long discussion about Sanitary Tees on their back for vent connections in a recent post. So, when I saw this, I assumed this was a vent connection, which in my world would be fine. But you know what happens when you ass-u-me something.

If this is a drainage line rather than a vent, for sure UPC 706.4, or whatever code is being used as they have similar wording, applies. "Vertical drainage lines connecting with horizontal drainage lines shall enter through 45-degree (0.79 rad) wye branches, combination wye and one-eighth bend branches, or other approved fittings of equivalent sweep."