Patio Bathroom Project

[thewoo81]

So i am building a large outdoor patio. Since we live in the Texas Panhandle, my wife wanted a tornado shelter. We purchased a 4'x6' above ground shelter and rather than just have wasted space, i am going to make a bathroom w/ a toilet inside. I have a couple of questions about tying into my existing plumbing line. As seen in the pic, the line will come out of the shelter and make a 45 and then out to the sewer line. Hopefully a few of you can chime in and offer a little advice.

1. Is there a minimum depth the sewer line has to be?
2. Can the sink drain into the vent line used by the sewer line? The 2 fixtures will be less than 6” from each other.
3. Since there are only 2 fixtures, can the vent line be 2”?
4. Since I am using 3” sewer line, is the drop still ¼” per 1’?
5. When I tie into the existing sewer line in the back yard, can it be a 90 degree elbow straight down into that line? If not, what is recommended?

 

[Pat the Plumber CIL]

In Illinois , 24" below grade is minimum outside building , Would think Texas is much less .
Yes sink can drain into vent that serves toilet , called a wet vent . Yes vent can be 2 " but in Illinois 3 " min out the roof (frost closure ) Can increase to 3 " in attic and then out roof .
1/4 inch per foot is min drop allowed for 3 " , 4" can be 1/8th outside building .
For the most part from horizontal to vertical can be a 90 degree elbow but I would use a 45 and street 45 and make a long sweep .

 

[frodo]

Texas is IPC
3'' slope is 1/8'' inside and outside the building
2'' vent is fine.
no minimum depth required

when you exit the new building. you are required to have a 2 way cleanout within 5' of the building
instead of a 90 into the sewer