Forum Title: Installing drain and running water lines under concrete
Hello all, any advice is greatly appreciated! I am in the process of adding an in-law suite in my basement. Adding a small kitchenette. I've trenched through the slab to the bathroom to connect the new kitchen sink to the existing drain line from the shower. 2 Part question below: 1. I think I am going to replace the three way sanitary T in the picture with a 4 way T to accommodate the new pipe from the kitchen sink. The pipe leading down into the existing T is from the bathroom sink, and pipe coming from the right of the picture is from the shower drain. These pipes are cast iron and I will be splicing in a PVC connector. Is replacing this 3-way connector with a 4-way connector the best way to add this new kitchen sink drain line to the existing drain? Is there an "easy way" to cut cast iron pipes? I was planning on using a reciprocating saw. Please let me know if I am missing something or setting myself up for failure. 2. Second part of the question...The two vertical copper lines behind the drain pipes are the hot and cold water lines for the bathroom sink. I was planning on tapping into these and running PEX tubing to the kitchen sink location. Multiple questions here...Can I use PEX tubing in the dirt under gravel and concrete? What kind of connector should I use where I splice into the hot and cold lines (considering this connection will be eventually covered in dirt and concrete as well)? Should I run the PEX tubing in some sort of rigid conduit to keep it from collapsing? Thanks for the help. Please feel free to poke holes in my plan and offer any suggestions. Obviously I am not a plumber, just a homeowner with a DIY background.
Category: Plumber Post By: JOY TERRY (Brownsville, TX), 07/09/2017

Frodo nailed it using a wye with a 45. The existing combo servicing the bathroom sink should not be touched. That is an old technology using lead and yokum joints. Breaking the seal and causing a leak will create a nightmare for you to fix (you may have to yank out everything and reinstalling all new piping). To the left of that combo I see cleanout. That may be your best bet to make the tie-in somehow. As for using a reciprocating saw to cut cast iron I'm not sure it will cut it but you could try. A chain cutter is usually what I used to cut cast iron pipe. Good luck and keep us posted on the progress.

- JOANN MAY (Roswell, GA), 09/18/2017

thats not a tee, its a combo. if you replace a combo with a double combo. you need to see if the combo you are replacing is DEAD level. because, if one side of the double combo is raised, the other side is backfalling. so to answer your question,,not a good idea. remove old combo,,replace it with new, add a wye and a 45 for new drain..buckle them in with cast iron x plastic mission bands use pvc do not splice into the water line under the floor, loop the pex up into a wall, tie in above ground no joints under concrete

- LORETTA BECK (Edmonds, WA), 10/05/2017

I just thought of something. The cleanout is probably connected to another combo. See if you can remove the cleanout and use a sanitary tee to sit on top of the combo below. From there you can run your kitchen sewer line into the sanitary tee. Note that for waste line purposes a sanitary tee can be used upright (it cannot be laying down like a combo).

- BESSIE VAUGHN (Milpitas, CA), 10/09/2017

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