Main drain depth exiting cottage for septic line connection

Discussion in 'Plumbing Code Questions' started by chuck b, Jun 23, 2011.

  1. chuck b

    chuck b sea-bee

    Messages:
    76
    Location:
    levering, michigan
    Have smallish 650 sq. ft. cottage in Northern Michigan - seasonal for non-winter months.

    Replumbing entire DWV system, and need to know what depth to exit cottage for future new septic system (elevated-engineered system) connection.

    Have heard conflicting stories, e.g. top of (3" sch. 40 pipe in my case) at least 8" below ground level.

    Please advise. After exiting, will travel short distance to dousing tank - grinder pump then some 300' to field.

    Thanks.
  2. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,831
    Location:
    Cave Creek, Arizona
    You install the plumbing inside the building, and then they install the septic tank wherever it has to be so the pipe can be connected. I have had tanks 18" below the ground, and also 10' down when there was a basement.
  3. Smooky

    Smooky Member

    Messages:
    624
    Location:
    NC
    I would put it at least 12 inches deep so your tanks will be below the ground surface. The depth of the tanks should not matter unless you have bedrock near the surface or a very high water table that could cause installation problems etc. Since you are pumping the sewage the depth is not as important. Sometimes for a gravity system you would have to keep the plumbing high if the drain-field was being installed in a raised mound or required to be installed ultra shallow because of the water table etc.
  4. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,831
    Location:
    Cave Creek, Arizona
    Since the opening in the tank is usually 12", OR MORE, below the top, a pipe 12" deep would put the tank at or above the ground level.
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