Basement bathroom help

[jer42]

Hello all! I'm new here from Illinois. Found this site while trying to figure out how I was going to run the sewer lines in my basement. Was hoping someone here would be able to help.

Below are pictures of what I have in my basement. I will be installing a tub/shower and a toilet on one side. On the other I will have 2 sinks. My question is how do I know if the tub and toilet drains are vented? Also can I dumb the sinks into the 2" pipe (which I believe runs up to vent the bath upstairs) or do I have to use the 3" pipe that the upstairs tub and toilet dump into? Any answers will be greatly appreciated. Thanks!

[hj]

If the pipes are not there already, then YOU will have to do the piping to vent EVERYTHING. vents do NOT run up to a tub. You cannot use EITHER pipe for the drains unless you vent them. It appears that this is NOT an ideal DIY project for you. Call an expert plumber, (not "Joe's, I do everything"), to avoid making major mistakes.

[jadnashua]

It appears that both of those lines are already drains, and thus, cannot be used as vents. You should be able to tell if you listen carefully next to them while someone goes around and runs water through various fixtures in the house. This does not mean you need a new hole in the roof, but you must run a new vent line up high enough in the house to then, either go through the roof on its own, or connect to an existing vent. Unless you have plans, and preferably pictures, there's no easy way to tell where those drain lines go underneath the slab.