Very tight sewer line to toilet connection

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durm, nc
Searched through the forums and couldn't really find a situation similar to this one.

The blue line is where the 4in sewer line will be below the slab. The cross hairs at 20" and 14" (1" to allow for mud board and tile) are where I would ideally like to place the toilet. The sewer exits to the top of the diagram. (Aside: It currently dives vertically under a crazy 20" elevated slab about 10in from the wall and goes up about 6ft, then across the entire room, blocking windows, etc - total mess. I'm having the big slab removed and plan to re-route the line under a new slab, probably at 1/8" over 12" slope since the line is a bit high where it exits the house.)

The difficulty here is that the centerline of the sewer line is at 16.25". That ain't gonna work. SO, I guess the only other thing would be to add a pair of 45s in there:

Or perhaps just a wye for the 3 bathroom fixtures (toilet, sink, shower), leaving the main 4in as a straight shot. There will also be laundry coming in, but up near the top of the diagram.

I guess my question is, which is better, re-routing the whole 4in line (which serves the entire rest of the house), or just adding this branch? By "better", I mean optimal flow, best practices, etc.



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You want to run the bathroom stuff thru a backwater valve. The "normally open" type is better.

How deep is the blue line sewer line? If deep enough, you can have pipes cross over the top of that.
Hey, wait a minute.

This is awkward, but...

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