I am building a 30X40 shop with a living quarters framed in at the rear. I understand that the DWV line can pass through the footing of a monolithic slab. Most of my fixtures run along the load bearing wall nearest to the septic tank location. Can I run the 4" main down in the footing trench for an extended distance.. say 12 feet? I have a toilet, lava, shower, and kitchen sink that need to exit towards the septic tank, but if I route each drain down through the perimeter load bearing wall, they will be located within the footing. I'm outside the city limits in Arkansas so I don't believe code is a problem.. just want the install to last the test of time. I have heard not to run water supply lines within footing... they can only pass through with a sleeve. I was just wondering if drain lines were to be treated the same. Thanks for any advise... Jon

Are you asking to run the main in the foundation trench and pour a fotter over it?"
Let me know, Tom

I'm not familiar with what a fotter is? But, yes... I would like to run the main down in the foundation trench. I'm worried that the crush pressure may cause a problem with the PVC.

My ultimate question is this... the footing of this monolithic slab will have a height of 18" and be 24" wide. Most all of my fixtures are positioned over this footing and need to drain to the septic tank. The footing takes up so much room that I'm not sure how to route the main. If I just pass the main through the footing once at a 90 degree angle, the fixtures would have to drain towards the center of the slab and then make a 180 degree turn to head back towards the main in order to stay out of the footing. It just seems like there would be a much more logical way to route this plumbing.

Thanks, Jon

That word should have been" footer".

Most all of my fixtures are positioned over this footing You don't mean directly above the foundation do you? Why is the footer so wide? How many stories is it supporting? Have you considered running the main inside the pour and 45ing out of the foundation to get to the septic tank? Regards, Tom

I was told by the builder that 18"x24" was pretty standard for the footing. This will be a 30'x40' steel building (single story with 16 ft eaves). Buildsite is on top of a large rocky hill and has been dozed nice and level. I am a die hard do-it-yourself guy so it kills me to pass the buck. I've checked out half a dozen plumbing books at the library and have spent hours researching online, but I may have to bite the bullet and hire a professional plumber to at least rough in the ground work. 45ing may be the way to go here. If I do make a single 90 degree pass through the footing with the main, should I go with a cast iron sleeve or would a PVC sleeve be sufficient?
Thanks, Jon

Hello Jon... In my area, you have to penetrate load-bearing foundation in the most direct way or you will create "weak point" , therefore jeopardizing the load-bearing integrity of the foundation. Like Tom suggested in his previous post #4, you can run the main run either on the inside or outside of the foundation. Preferable would be on the outside of the foundation bcs it will be accessible for future service. You will have to run vents, and sink drain upward through the foundation. This is OK. Any pipe within the foundation has to be wrapped with approved Foam Wrap to separate concrete and pipe.

I drew a simple drawing for you so you better understand and to give you some visual...

Thanks Milo... the drawing really helped! I like the idea of having the main outside the foundation. I'm assuming the green oval is a clean out. I believe I can rough in the ground work now. Thanks again, Jon

Yes, that is correct: the Green Dot is main Clean out...

Good luck with your project. Let us know how you did ! Milo