Bathroom Plumbing Help

Hi everyone. I need some plumbing advice on venting and drainage. In the attached photos the red line is the current plumbing drain run with vertical vent visible. I need to move the shower drain to where the green circle is located. What is the best way to do so? Can the shower drain be between the vent and toilet (my guess is no as it will get sucked dry)? Does the vent need to be between the shower drain and toilet? This answer will lead to follow ups about which fittings are permitted and which I should use.

Please don't judge this current setup, it was not done by me, but the last owner. Let me know if you'd like more photos/info

 

What is the diameter of your shower drain pipe?

It looks like all your doing is moving the shower drain 9-12". Measure the shower drain line length from it's new location to the vent. If your shower drain pipe is 2" then your shower drain can be up to 5' from the vent.

I would pull up some for subflooring for a better look. The drain line location your marked in red and the existing shower drain path don't make a lot of sense.

 

The drain line is only 1-1/2 unfortunately.

I know the existing drain line location doesn't make a lot of sense, but that is 100% accurate. I know I need to open up the subfloor in the next joist bay, but wanted to have a plan before hand.

I've attached what I think are my two options. My concern is with venting, as I don't want the toilet to suck the shower trap dry when flushed. Is there anything wrong with using a Wye to tie into the main line in Option1?

 

Since the existing shower drain is under-sized, I would definitely go with the wye has you have it drawn - as long as you can get it positioned correctly. The toilet vent (and new shower drain) should both be 2".

I assume the drain down to the main sewer is behind the toilet (and not where the vent is)