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Thread: New Bath In Basement...Ejector Pump/Pit tie in

  1. #1
    DIY Junior Member EJG1447's Avatar
    Join Date
    Mar 2010
    Chicago, IL

    Default New Bath In Basement...Ejector Pump/Pit tie in

    I am adding a bathroom in my basement. After much research I decided to go the sewage ejector pump/pit route. I have a 90 year old bungalow with a 4" cast iron soil stack and 2" galvanized vent. The main floor bath is directly above the new bathroom location. When we bought the house, there was a toilet only in the basement. After breaking the concrete around the stack and digging around I found the 4" cast iron transitioning to 6" clay (via a 4" sanitary tee w/ a 2" side inlet) and then out to the city sewer. I didn't like possibly damaging the clay so I went with the pump/pit option. I have the DWV system designed & dry fitted which brings me to my questions (I will post pics when I get a chance) :

    1) I have cut off the original closet flange to make room for the new toilet location. Is a fernco cap suitable for under slab application?

    2) I was thinking of cutting a no-hub 4" c.i. wye and then tying the sewage discharge into that. Since I have to cut into the 2" galvanized vent to tie in my new vents anyway, can I use the remaining stub coming up from the original sanitary tee w/ side inlet as my tie in from the pump?

    3) I read that the pump/pit should be vented separate from the rest of the venting, however this isn't really feasible. Why is it not ok to tie into the same vent? Can I vent out the side of the house?
    Last edited by EJG1447; 04-12-2012 at 06:08 PM.

  2. #2
    Retired Defense Industry Engineer jadnashua's Avatar
    Join Date
    Sep 2004
    New England


    When the pump runs, the vent is required to allow air to come in to fill the pit, otherwise, it would be creating a suction. It needs a proper vent (an AAV won't work, as it won't allow air to escape to enable the waste to come in in the first place). Now, whether that can tie into the existing one or not, I'm not sure...the pump could create a fairly significant suction, which could disrupt the trap seals in anything else attached to it.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  3. #3
    Moderator & Master Plumber hj's Avatar
    Join Date
    Aug 2004
    Cave Creek, Arizona


    If the venting is done properly, there is NO ordinally suction which should disturb trap seals, although we COULD do it with powerful vacuum pumps at the testing laboratory.
    Licensed residential and commercial plumber

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