Swap Toilet and Shower Locations

[2BPS]

I'm doing a bathroom remodel in which I plan to swap the locations of the toilet and the shower. All of my DWV is ABS and it is located in an accessible crawl space below my single story house. I believe the swap is going to be pretty straightforward but wanted to make sure I'm not missing something.

In this post I will ask about the drain for the new shower. Here is a photo of the existing toilet and lavatory drain. The toilet is 3" on the right, then meets the 2" vent which is also the lavatory drain. Then it flows west to my septic tank.



Now I want to remove the toilet and put a shower drain in its place. Assuming the maximum dimension to the vent is not exceeded, is there anything wrong with doing it this way? I'm hoping I can still use the same shared vent (shared with the lavatory) for venting my new shower and not have to vent it separately.

What's the cleanest way to tie in the new shower drain? It will be 2" ABS. What fitting(s) would you recommend to transition the new 2" shower drain into that existing 3" line (where the toilet currently connects)? The new shower drain will be in the same N-S plane as the toilet drain, but about 18" farther south (away from concrete foundation) than the existing toilet drain.

Thank you for any input/advice.

Heidi

[Terry]

You could place a santee on the 45 section of pipe for the shower if it's within 60"

The 45 degree pipe is considered vertical.

[2BPS]

Terry,

MUST the new shower drain tie in to the 2" vent (vertical or 45 deg) or would it also be acceptable to tie in farther east, into that horizontal 3" line that currently services the toilet?

Thanks,
Heidi

[Terry]

would it also be acceptable to tie in farther east, into that horizontal 3" line that currently services the toilet?

That depends on what you are doing with the toilet.
If the shower is the only fixture, then yes you can cut in a p-trap for the shower there.
The lav still wet vents it as long as nothing like a toilet comes between it and the shower.

[2BPS]

HOORAY! This is the answer I was hoping for.

The toilet will be elsewhere and has its own vent. So it will just be the shower then the lav (both sharing the lav vent).

Thank you so much!
Heidi

(P.S. I really don't understand why my current setup, with toilet upstream of lav, was allowed. I thought that was forbidden.)

[Terry]

(P.S. I really don't understand why my current setup, with toilet upstream of lav, was allowed. I thought that was forbidden.)

The lav wet vents the toilet.