Plumbing: adding onto a horizontal toilet drain

Discussion in 'Illinois Plumbing Code Questions' started by fordperson, Apr 22, 2019.

  1. fordperson

    fordperson New Member

    Apr 22, 2019
    Hi everyone,

    Currently I am redoing a small shower which had a bathtub and toilet. The tub was the standard 1 1/2 drain and now I would like to convert it to a full 2" if possible.

    Running a new 2" pipe all the way to the vertical stack is quite impractical so I am looking on advice on running the 2" drain into the existing 3" toilet pipe.

    Here is the mock up picture for reference. I would wye the 3" using a 3-3-2 and use the 2" leg for the shower drain. From my understanding the 2" pipe needs to be vented separately so I would use the previous 1 1/2 vent for that purpose.

    PS Location is naperville,il

    Hope I made it clear, thanks a ton again.

    Attached Files:

  2. fordperson

    fordperson New Member

    Apr 22, 2019
    Just to add to this a bit, is the 2" drain required by code? I found this in the pluming code, but I am not sure if it indicates the whole run needs to be 2" or just the drain flange.

    Section 890.690 Shower Receptors and Compartments
    a) Shower Installation. All shower compartments, except those built directly on a
    slab floor or having receptors constructed of precast stone, terrazzo, concrete,
    molded stone, molded fiberglass, or an equally durable material such as cultured
    stone or synthetic stone, shall have a lead, copper, ABS, PVC or fiberglass
    shower pan. (See Section 890.230 entitled Safe Pans.) All sides of the shower
    pan shall turn up at least 2 inches above the finished shower floor level. Precast
    molded receptors shall have a minimum ¼ inch thick flange. Traps shall be
    constructed so that the pan is fastened to the trap at the seepage entrance, making
    a water-tight joint between the pan and the trap. Shower receptacle waste outlets
    shall be at least 2 inches in diameter and have a removable strainer.

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  4. hj

    hj Master Plumber

    Aug 31, 2004
    Cave Creek, Arizona
    WHERE is the "Y". They probably would NOT allow that low inlet 1/4bend for the toilet, for several reasons. But, if they did the shower WOULD need its own "proper" vent.
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