Under Slab Plumbing - New Construction

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by jimpargolf, Jun 3, 2017.

  1. jimpargolf

    jimpargolf New Member

    Joined:
    May 27, 2017
    Location:
    Arizona
    I am getting ready to build a new home and have a question about the waste pipes under the slab.
    Attached is the (very preliminary)plan showing the layout. I put the Septic tank near the garage so any future pumping allows access. Can I run the waste pipe from BR3 (top left) - it goes under the slab, then partially under the open air courtyard and again under the slab. Is this allowed ?Also, I am planning on a future guest house (1BR,1BA 650sqft, kitchenette) on the top of a hill about 75' away. Can I tie in the waste line from the guest house to the main house (as shown on the drawing) ? Or a separate septic tank for the guest house ?
    Thank you!
     

    Attached Files:

  2. MACODEDOC

    MACODEDOC New Member

    Joined:
    May 28, 2017
    Location:
    Massachusetts
    IF THE PIPING IS DONE THE WAY IT IS SHOWN I WOULD ALLOW IN MY JURISDICTION, I ALSO WOULD ALLOW THE GUEST HOUSE TO BE TIED INTO A SINGLE SEPTIC TANK IF SIZED PROPERLY. I HOPE IT HELPS
     
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  4. jimpargolf

    jimpargolf New Member

    Joined:
    May 27, 2017
    Location:
    Arizona
    Thanks for your reply...Now I've added a bit more detail to show the DFU's and pipe size. In California, they allow 34 DFU's on a horizontal 3" pipe. I have 2 options - keep it as shown with the guest house tying in at the septic tank or option 2 - tie it in at the upper left cleanup location. This would be shorter trenching but exceeds the allowed 34 DFU's for 3". Then as I understand the code, I can keep 3" pipe until I exceed the 34DFU's which would occur at the bathroom on the upper right. From there, I would need to have to use 4" from the bathroom tie in to the septic. Is that correct? Also, I understand I need a cleanout at the upper end (which I have) and then every 100'. I added a cleanout pipe that is accessed from the courtyard to the main pipe. I also have a 2 way access pipe just outside the house. That is what I understand the code to be. Correct ?
    Lastly, does the overall pipe layout look correct (efficient) ? The one area I think I could improve upon is going from the upper left. Instead of angling down I could just go straight down and tie it in near the washer/dryer. Less trenching/pipe. Thoughts? Suggestions?
     

    Attached Files:

  5. jimpargolf

    jimpargolf New Member

    Joined:
    May 27, 2017
    Location:
    Arizona
    Would anyone recommend a 4" instead of 3" pipe ? Even though the house is fairly large, it is only planned for 2 people.
     
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