Hi- basically what I have is a second floor in a building which I am eventually going to rent out as an apartment.
I have hired a plumber to add hookups and drain so that the renters can have a washing machine and dryer- which I believe is worth the trouble. Too late for that debate.
Now, what I'd like to do is be prepared in case the (we assume to be) careless renters flood their washer.
Attached are pictures of what the plumber did both on the 2nd floor, and below the room downstairs which is a utility room. You can see the white drain pipe going around the ceiling of the downstairs room, and down into the septic stack. Also you can see upstairs where he added a venting stack for the drain. OK, he's a professional plumber, we assume he knows his stuff.
Now what I would like to do..... is put a drain next to the pipes upstairs, basically cut a hole in the floor for a 2" PVC pipe but, then where does it go safely?
If you look at the basement picture where the laundry drain connects to the stack [pic #4], you can see an unused black stack next to it, that tees into it. That's the obvious answer I would assume would work (tell me if you doubt)- connect floor drain to black stack. However......then I have to run an entire second 2" pipe all the way around the room connecting that to the floor drain, that only gets used on the off chance the upstairs washer floods. Expensive, takes up space, looks crummy too. Is there a smarter way?
What I would LIKE to do instead is tee off the plumbers washer drainpipe up at the top under the floor, combining the floor drain and the washer drain to one pipe [pic #2]. Simpler, uses a lot less space and money. My fear however is that when the washer is run, then water may overflow/back up the floor drain upstairs.
Can anyone tell me if this physically would happen, or not via gravity and physics? Obviously once I cut into the pipes and test, etc, its too late.