Drainage Water Test in Basement pre-slab rough-in

Discussion in 'IPC Plumbing Code Questions' started by mariposuerte, Oct 12, 2021.

  1. mariposuerte

    mariposuerte New Member

    Joined:
    Oct 12, 2021
    Location:
    Rosanky, Texas
    I am installing the basement drainage rough-in for our cabin in Colorado next week. The basement will have one bathroom group (WC, BT, Vanity) plus a utility sink that will share the vanity drain/vent. This will connect to a sewage ejector basin about 20 feet from the bathroom then will be lifted about 5 feet to the main septic line to the septic tank. At this stage we are just installing the under-slab components and I am good with the drainage lines and venting for the basement fixtures but the CO inspector did say we would need to complete a drainage water test as listed in IPC 312.2 drainage and vent water test. I have never done a water test on a drainage system and was wondering what this should look like. We will just have stubs that will come out of the slab for all the fixtures/vents and the sewage ejector basin at this stage prior to preliminary inspection. To complete the water test with not less than 10 feet of head of water do we just add a 10 foot section to a vent (or fixture) stub and plug all other fixture/vent stubs along with a plug at the basin inlet? I can't find any pictures or videos of this online in my searches so was curious as to how this should look for this section of the drainage piping. Any input would be appreciated.
    Thanks!
    John
     
  2. Reach4

    Reach4 Well-Known Member

    Joined:
    Sep 25, 2013
    Location:
    IL
    You need to block off things so you can fill the system up with water up to the roof vent I think.
    You have seen closet flanges available with knock-outs. That's why those are available. So there are various ways to plug pipes, including "test balls" with Cherne being a big name in that.

    There are "test tees" that have special features to help block water at that point, and then that tee can serve as a cleanout port after the testing.

    A water test shall be applied to the drainage system either in its entirety or in sections. If applied to the entire system, all openings in the piping shall be tightly closed, except the highest opening, and the system shall be filled with water to the point of overflow. If the system is tested in sections, each opening shall be tightly plugged except the highest openings of the section under test, and each section shall be filled with water, but no section shall be tested with less than a 10-foot (3048 mm) head of water. In testing successive sections, at least the upper 10 feet (3048 mm) of the next preceding section shall be tested so that no joint or pipe in the building, except the uppermost 10 feet (3048 mm) of the system, shall have been submitted to a test of less than a 10-foot (3048 mm) head of water. This pressure shall be held for at least 15 minutes. The system shall then be tight at all points.​
     
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  4. mariposuerte

    mariposuerte New Member

    Joined:
    Oct 12, 2021
    Location:
    Rosanky, Texas
    That is what I was thinking but couldn't find much about it online. Since we will just have an excavated area for the basement we can probably get by with a 10 foot extension on the lavatory/utility sink 2" drain line since that will be the highest point of the basement drain section prior to getting the slab poured and the house framed in. I will plug the BT, WC stubs and the inlet to the sewage ejector basin for the water test either by capping the pipe which we can cut off later or with a test plug (sewage ejector basin inlet) and/or knock-out flange for WC. I have a 12 foot stepladder onsite so that can provide access and support for the temporary extension for the LAV drain with extension to provide 10 foot head of water to complete the water test for the inspector. Once the house is completed we will have to do the water test on the rest of the drainage piping along with any other required tests, but that will be next summer. The house will have a loft as well as the basement so the roof vent will be around 32 feet up from the basement which would be tough to support with no framing. I guess that is why IPC allows you to do it in sections with a minimum 10' head of water. Let me know if you see anything I missed. Thanks for the input, I appreciate your feedback.
     
  5. mariposuerte

    mariposuerte New Member

    Joined:
    Oct 12, 2021
    Location:
    Rosanky, Texas
    Take a look at my basement drain and venting plan with the main question being the BT vent. I should be fine with wet venting this through the vent right after the WC? The WC is inline with the main drain 3" line but is offset in the picture for viewing purposes. I know we could get away with a smaller vent size, but 2" was as easy as 1.5" for this application and it will give me more distance to run this vent section.
    Comments and advice are appreciated. IPC code for Colorado.
     

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  6. wwhitney

    wwhitney Well-Known Member

    Joined:
    Mar 17, 2019
    Location:
    Berkeley, CA
    Yes, the IPC allows a dry vented WC to wet vent the bathtub. The bathtub trap arm still has to meet the usual requirements: at least 1/4" per foot of fall, but no more than 2" total fall from the 2" trap to the horizontal wye where the WC wet vents the bathtub.

    Cheers, Wayne
     
  7. Jeff H Young

    Jeff H Young In the Trades

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    Feb 27, 2020
    Location:
    92346
    I notice you have a 2 inch trap arm and 1 1/2 trap for tub, I've always matched my trap to the trap arm size . might want to check code
     
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  8. mariposuerte

    mariposuerte New Member

    Joined:
    Oct 12, 2021
    Location:
    Rosanky, Texas
    Thanks. My Dad was planning to install a 1 1/2" trap in the BT box to give some play with the connection. I saw in IPC 709.1 we could use 1 1/2" for BT and 1002.5 size of fixture traps says a trap shall not be larger than the drainage pipe to which it discharges. The plan was to put the trap in the BT box that I will install level with the slab. 1 1/2 " trap will connect to 2" drain line and would fall 1/4" per foot with total fall around 3/4" to 1" before the wye on the 3" line. For rough-in pre-slab inspection I was planning to cap the BT 2" line in the box which we would remove later to install the 1 1/2" trap to connect BT drain. Is this acceptable or do we need the 2" trap for the BT for this application?
     
  9. wwhitney

    wwhitney Well-Known Member

    Joined:
    Mar 17, 2019
    Location:
    Berkeley, CA
    Sounds like IPC allows a 1-1/2" trap on a 2" trap arm. So your choice, if it fits I don't see a downside to a 2" trap. My understanding is that slip joint connections should stay accessible, so if your tub trap is going to be inaccessible in a pit in the slab, you'd want to use all glue joint connections.

    Cheers, Wayne
     
  10. mariposuerte

    mariposuerte New Member

    Joined:
    Oct 12, 2021
    Location:
    Rosanky, Texas
    Good advice. We will go with 2" trap if it fits. The plan is to glue the trap joint connections just prior to tub install to aid in tub drain alignment since that can be tricky. I can put an access panel on the tub wall (opposite side of tub) which would make everything accessible and is probably a good idea even with glued trap joints. Thanks all, this has been helpful.
     
  11. mariposuerte

    mariposuerte New Member

    Joined:
    Oct 12, 2021
    Location:
    Rosanky, Texas
    One other question. We will be putting in a tankless on-demand water heater and water supply pressure tank in the utility room in the basement. Should I install a drain in that area leading to the basement ejector basin as well?
     
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