[captainbonko]

Hi,
I am planning to turn the half bathroom into a full bath in my basement. The floor is concrete. I've attached a jpg to illustrate the layout of the fixtures and septic. I was hoping to get some advice as to...
... which drain line to tie into
And
... the best position in which to orient the tub drain (ie close to the cinder block wall or away from it).

Your advice will be much appreciated. In fact, taking my jpeg, drawing over it, and posting it in a reply would be a plus!

Any other information about the access panel or box I need to make around the drain would be welcome.

Thanks for your time,
Joe

(all of the walls, save for the cinder block wall, are open and accessible)


Also... if you have any pointers as to which direction the pipes run from the existing drains, that'd be great. This way when I go searching, I can make more than just my best guess but one that comes from those more expierienced

[speedball1]

Locate and connect the tub to the lavatory drain line where it will be wet vented thus saving you from having to vent the tub. Break the cement starting at the base of the lavatory and work over to the tub trap. Here's how we rough our bathrooms.(see image). Good luck Tom

[CHayn]

Does your septic line go out through your wall? If so, where is your ejector basket located for the basement bath?

[captainbonko]

does your septic line go out through your wall? If so, where is your ejector basket located for the basement bath?

No, not that I know of. It goes out underground

[CHayn]

there is probably a 3x2 or a 4x2 wye on the drain from the toilet that catches the lavatory and wet vents the toilet. Your best bet is to tie the drain for your tub or shower into this 2" line to the lavatory that way you are venting your tub through the same line as well. See Speedballs image. I would put your tub valve and drain opposite the block wall so you would have more room to work installing the drain and valve.