Connecting 2" PVC to 4" Stack under Concret

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by Manish, Jun 7, 2007.

  1. Manish

    Manish New Member

    Hi Everyone,

    I have taken up a project that involves adding a Shower to my Basement which has concrete floor we had half Bath, I have removed the walls around it and vanity currently am at a point where have to break up concrete floor to connect a 2" PVC pipe for the shower to one of the following points and need help.

    I have a pit with up flushing toilet as the Sewer line is above the concrete floor level.

    1. Break concrete 8 foot long 4 " Deep to the pit


    2. Break Concrete 2 Foot long 4" deep to a PCV Stack 4" behind the toilet this is used as a vent I think as one end leads to the roof and the other to the pit.

    if I go for the near location how do I cut a 2" hole in the stack to connect the 2" PVC pipe to the bath ? is this the correct approch ?

    Trap will be installed at the shower end if thats OK.

    thank you

  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    New England
    If I understand this properly, if you connected to the vent for the toilet, it no longer is a vent...not good. Now, you say upflush toilet, but then you indicate an ejector pump. To me, this implies a normal toilet that drains to the sump. You can connect the shower to that drain. You need to provide both a trap under the drain for the shower and a vent. Depending on the layout, the toilet's vent might work, but I think not. A toilet normally doesn't require a 4" vent (except maybe where it goes through the roof). Maybe a little more description of what you have is in order.
  3. Gary Swart

    Gary Swart In the Trades

    Yakima WA
    Forgive me, but from the questions you ask, I think you are too much of a novice to take on this project alone. There are several places where you could go astray, leaving you with some real problems. I suggest you contact a licensed plumbing contractor to at least advise you on this job.
  4. Manish

    Manish New Member


    I do not know all the technical terms in Plumbing but I will try to explain this more as I know a lil bit more after digging out the concrete.

    The PIT is located right corner of the room appx 6 ft from the toilet

    1. The Basement has a PIT with a pump built in it once full it flushes the stuff to a sewer drain above ground.

    2. Distance toilet to PIT appx 6FTthe Sink or wash basin is 8Ft from the PIT

    3. Sink or a wash basin use to be 8 Ft from PIT and use to connect to a 4"
    PVC using a 1 1/5" PVC pipe using a T located behind the Toilet in the wall.
    yes there was a S TRAP.

    4. The 4" Pipe is located 1 Foot behind the Toilet appx 8 Foot front the PIT
    goes in 2 direction 1 to a VENT the other to the PIT.

    I did dig out the concrete and there is a 4" Elbow from the 4" PVC and a straight pipe that connects to the same pile as the toilet which leads to the PIT.

    I am think 2 options use a Saddle to connect the Shower to the 4" Pipe that leads to the PIT or cut a 2" hole in the 4" PVC pipe and screw a connector.

    I would appreciate any help you can provide. I can post picture if it would help.
  5. Manish

    Manish New Member

    Thx for your comments


    thx for your coment, I am a computer Tech very focused in firewalls etc, I believe one must constantly learn as one grows and where there is a will there is a way.

    I don't mean to be rude or brag but due to a contractors error I have ended up installing OAK floors total 4500 SQFT, built full OAK banisters and staircase 3 stories Victorian, remodel 1 bath not involving concrete, Painted 4BHK house, rewire 2 houses so far from bottom up, Installed a new Roof and the list goes on.

    So now trying to do as much as I can myself.
  6. kordts

    kordts In the Trades

    exurban Chicago
    A saddle is illegal, and I can't imagine how you will "cut a hole in the pipe and screw a fitting in." Unless you have the right size hole saw and 2" tap.
  7. Manish

    Manish New Member

    would it be a possible solution ?

    Yes I do have a hole Saw and if this is a possible solution than I would try it out on a scrap piece of PVC to make sure it would work before I do this on the final install location.

    Or should I dig out all the 4" PVC currently installed and install a 4" x 4" x 2" T ?
  8. Terry

    Terry Administrator Staff Member

    Bothell, Washington
    More that likely, what you would do, is to add a 4x2 wye behind the existing vent for the toilet.

    Wye behind the toilet vent, inserting with no-hub type couplings.
    Use a wye and a 45 fitting (combination tee wye, or combo fitting) on the 2" line to add a vent for the shower line and p-trap.
    Tie that vent back at 42" to the main vent. (toilet vent)
  9. Manish

    Manish New Member

    I knew I would get good advice around here

    Thank you Terry,

    I knew at some point if I keep trying I would get good advice here.

    If I understand this correct, the 4" PVC pipe goes in 2 directions
    1st shoots Vertically as a vent to the roof, 2nd end to the Toilet and continues to the PIT, So I would cut the PVC below concrete level on the PVC end that shoot towards the roof behind the toilet and add a Wye 4" x 2" and 45 fitting with a p Trap 2" to connect the shower drain is this correct ?

    What is a " inserting with no-hub type couplings" will a plumbing supply store know this item ?


  10. hj

    hj Moderator & Master Plumber Staff Member

    Cave Creek, Arizona

    If you are connecting to the vertical pipe, you cannot use a Y and 45 elbow. It has to be a sanitary tee. And depending on where you make the insertion will determine whether the added drain has to have its own vent or not. Plumbing is more than making stairways and bannisters.
  11. Terry

    Terry Administrator Staff Member

    Bothell, Washington
    hj is right, I was assuming that you would put a wye in the horizontal pipe in the ground. Then you would use a wye fitting.

    If you are venting a vertical pipe, it becomes a santee.
    Do you even have that much space that you can come off the vertical and still maintain your toilet vent seperate from a shower vent?
  12. Manish

    Manish New Member

    I Like your advise

    Hi HJ / Terry,

    Once again I appreciate your time and advise I want to do the right thing if you guys really think it is impossible for me to do this I will hire a plumber.

    I don't know if I mentioned this but ..

    The same Vertical 4" Pipe currently has a Y that connects the hand sink but at a higher level appx 1 foot above ground or concrete floor to drain waste water from the sink, I don't know if this helps you guys in any way.

    thx again.
  13. summary, review of options.

    hi manish!

    I can appreciate your thoroughness, and ability to learn new things while not overreaching. I hope this works out right.

    Seems to me, that you have a pit, that you have to get the shower drain water to go into, and that that shower drain needs a vent too so its route will have to be planned to go get new venting derived from the 4" vent beforehand. That is a revent loop.

    BUT, since you have a pit, maybe you don't need venting for the shower drain line prior to its connection to the pit, since the pit itself is a well-ventilated holding tank which performs the same function as a standpipe does for washing machines. That is something to analyze and check out. I don't have that level of knowledge; I know enough to think of asking that question. Planning venting is very important. (Confirm everything twice!)

    Your 4" PVC vent is good venting for an ejector pit. The principle of that pit is like the tank on a toilet; when its level rises, it triggers a motor. (On a toilet it triggers a stop fill). Pit venting is provided by the 4" pipe, which is closed off from the house air so smells (dangerous) don't get breathed.

    Seems to me your toilet's drain flows 4" under the surface of the concrete into the pit (tank). So, one obvious idea is to wye into the toilet's drain line which goes into the pit. But that absolutely does need new venting cut out of 4" vent at a high height and routed over to come down into the shower drain line (search "re-vent" loop) since both drains would then "share" a length of pipe for a segment. Then, if there is any segment of the toilet's drain that is vertical, you could use a San-Tee fitting, but you still need that re-vent. Now, here is my big question: is it really the only option to consider that you would cut into the toilet's drain before it runs into the pit? Why cannot you not consider running the shower drain into the pit by having a new hole made in the pit wall for that purpose? What is the pit made of? How much air (height) is left at the top of the pit when it is deemed full by its ejector pump trigger switch? Since the pit can receive a 3" diameter toilet drain pipe, it can receive a 2" shower drain pipe too. This may be the avenue to pursue. I am assuming that the pit was truly designed and built by professionals so it won't present problems. The fact that you have a 4" diameter vent is good news; it's so big that it can handle both a toilet and a shower.

    p.s. please post a line drawing of the floor layout plan, accurately positioning pit, vent, toilet, shower and handrinse sink. Top view.
    Last edited: Jun 11, 2007
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