Backwater Valve

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by dlarrivee, Nov 14, 2009.

  1. dlarrivee

    dlarrivee New Member

    Messages:
    1,172
    Location:
    Canada
    Is there anything wrong with installing a 3" ABS back water valve in a drain that is not below a concrete slab?

    [​IMG]

    This is the style I am speaking of, and they usually come with a sleeve and cap meant to be cut flush with the top of the slab...

    This is the 3" into 4" waste line exiting my house. The 3" line is 20" from the slab. (bottom right corner)

    [​IMG]
  2. Doherty Plumbing

    Doherty Plumbing Journeyman & Gas Fitter

    Messages:
    810
    Location:
    Penticton, BC
    This is perfectly fine! In fact it's done all the time where a backwater valve is called for and the sanitary building drain leaves the building.

    I don't know about codes in the USA but in Canada there is absolutely nothing in the National Code book that says a back water valve shall be installed in the ground. In fact you're able to use them quite frequently in all sorts of places if you want to as long as you meet a few code requirements.

    Just make sure you install a back water valve that is "normally open" and you should be just fine.
  3. dlarrivee

    dlarrivee New Member

    Messages:
    1,172
    Location:
    Canada
    Great thanks.

    I am actually located in British Columbia.

    The only thing that bugs me about this type of valve is that if it we're to become inoperable at any time you cannot replace just the flapper, you have to cut the entire thing out.

    Unfortunately most of the "serviceable" types don't seem to come in 3"?
  4. Doherty Plumbing

    Doherty Plumbing Journeyman & Gas Fitter

    Messages:
    810
    Location:
    Penticton, BC
    Hey sorry I didn't see that.

    I am in BC as well (Okanagan area). Putting a BWV there is perfectly acceptable.

    3" is some what of an "odd ball" size. There are lots of times you'll find something in 4" but not 3". Just because they sell a heck of a lot less 3". I wouldn't install 3" in a new house today. Everything would be 4" that was required to be 3".

    Don't worry too much about it acting up. Just install it and forget about it :D

    OR You can redo the connection to the 4" and replace a bunch of that 3" with 4" and install a 4" BWV that's serviceable. But that 4x3 wye looks pretty tight up against your foundation wall!
    Connect to the 3" with a 4x3" coupling and you'll be perfectly acceptable code wise doing this as well.
  5. dlarrivee

    dlarrivee New Member

    Messages:
    1,172
    Location:
    Canada
    I'm located in Kelowna actually.

    The only problem with redoing a bunch of that line in 4" is that the wye that is halfway embedded in the concrete is a 4x4x3 and would need to be replaced as well... Just to much work for a certain style of valve to go in, not worth the effort.
  6. Doherty Plumbing

    Doherty Plumbing Journeyman & Gas Fitter

    Messages:
    810
    Location:
    Penticton, BC
    Penticton here. I would agree with you and just go with a 3" valve!
  7. dlarrivee

    dlarrivee New Member

    Messages:
    1,172
    Location:
    Canada
    Also, is there a certain distance that a backwater valve must be away from any drain branch into the waste line?

    [​IMG]

    I want to move the washer and dryer this corner as well, but I'll need to add a new drain for the washing machine...

    Can I have a wye right beside the backwater valve?
  8. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,605
    Location:
    Cave Creek, Arizona
    Bwv

    The question is not whether it is okay to use it or not, the real question is WHY would you do it. Unless you have some situation not shown in the picture, you have an "overhead" sewer, and as such there is nowhere for the water to overflow into the basement. An overhead sewer will continue to operate normally, even during a main sewer backed up condition, BUT if you install a backwater valve in it, THAT will prevent you from using ANY water in the building during a main backup condition.
  9. dlarrivee

    dlarrivee New Member

    Messages:
    1,172
    Location:
    Canada
    I have a sewer ejector pump located below the slab for the basement bathroom, there's a trap and stand pipe for the washing machine in the basement as well.

    It looks like it's damn near impossible to find a normally open 3" anyways...

    Should I be looking at just installing one between the ejector pump and the main drain, I believe it's 2" abs... I could use a normally closed valve in this situation and not damage it, if the lines ever needed to be snaked...
    Last edited: Nov 15, 2009
  10. Doherty Plumbing

    Doherty Plumbing Journeyman & Gas Fitter

    Messages:
    810
    Location:
    Penticton, BC
    Your ejector pump by code should already have a check valve installed on the outlet of the pump. I'm sure it does if you don't notice your pump cycling on and off every 10 seconds :p

    A backwater valve when you're below grade is never a bad idea! If your street's main ever backs up guess where that sewage is gonna go? To the lowest point and your house is one of those low points.
  11. dlarrivee

    dlarrivee New Member

    Messages:
    1,172
    Location:
    Canada
    If it does indeed have a proper check valve on it, it must be hiding or integrated into the pump itself.

    Doherty, you mentioned I should make sure I use a normally open style, I don't see anything available in 3" that's normally open..?
  12. Doherty Plumbing

    Doherty Plumbing Journeyman & Gas Fitter

    Messages:
    810
    Location:
    Penticton, BC
    By code any backwater valve you install must be of the normally open kind.

    You don't see anything coming out of your sump that looks like it could be a check valve? In these parts we usually use a white pvc compression style check. If you don't have one you should look at installing one....

    I can check with my local wholesaler in town here and see if I can find a 3" normally open valve. If I can get ahold of one I can always buy it for you and ship it to you. It'll cost you a bit extra but then atleast you'll have the right part.
  13. dlarrivee

    dlarrivee New Member

    Messages:
    1,172
    Location:
    Canada
    The only normally open one that I have found is the big mainline style with the clear top...

    I'll have to investigate further the lack of check valve, is it possible that it has been installed below the lid of the tank?
  14. Doherty Plumbing

    Doherty Plumbing Journeyman & Gas Fitter

    Messages:
    810
    Location:
    Penticton, BC
    Yes very possible. I am sure you have. You can test yourself by simply having the pump kick in and let it run till it pumps the sump dry. You shouldn't hear much water draining back into the tank once the pump kicks off. You will hear a bit (the water between the pump and check valve). If you have no check valve you'll more then likely hear a decent amount going back into the sump because you will get the water from the pump to highest vertical portion of the piping (before it starts grading down horizontally) draining back into the sump.

    If you try this and you can't tell or are unsure just pop the top of the sump off and take a picture!
  15. dlarrivee

    dlarrivee New Member

    Messages:
    1,172
    Location:
    Canada
    It's not looking good in the check valve department...

    [​IMG]
    [​IMG]
  16. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,605
    Location:
    Cave Creek, Arizona
    check valve

    Normally the check valve would be installed with rubber vibration dampers. You have a poorly, AND improperly, installed pump. Without the check valve you might need the BWV, but only because any main sewer backup will flow DIRECTLY into the basin and if the power is off so the pump cannot push it back out, it will overflow. But, otherwise you do NOT need a BWV, and installing one would make your system less reliable, not more so. At this time, you can use ALL your plumbing normally, or at least should be able to if the drainage we cannot see is installed properly, but if you install a BWV, you will NOT be able to use ANY plumbing, including the ejector pump, in the house until the flooded condition subsides.
  17. dlarrivee

    dlarrivee New Member

    Messages:
    1,172
    Location:
    Canada
    hj, I realize that the ejector pump is lacking a check valve, but beyond that is there anything else you see in these picture that makes you say it's improperly installed?
  18. Doherty Plumbing

    Doherty Plumbing Journeyman & Gas Fitter

    Messages:
    810
    Location:
    Penticton, BC
    Hey,

    To meet code here in BC you should have a union, check valve, and shutoff installed in that order in the direction of discharge.

    There is nothing about your install that goes against code otherwise. It may not be piped in the best way it could but what you have (when you get the stuff I listed installed) would pass a plumbing inspection.

    If I had installed it I would have come up higher with the pump discharge pipe and dumped it into the main from the top down, not on the side.
  19. dlarrivee

    dlarrivee New Member

    Messages:
    1,172
    Location:
    Canada
    I picked up a check valve at the store before I read your post, and it's about 9.5" and has rubber ends with stainless steel clamps.

    I've never seen an ABS union though, other than 1 1/2" ones on traps.

    I guess I could use PVC pipe from the pump, put a PVC union then a short chunk of pvc, my check valve, and then hopefully I can find an ABS gate valve?

    Are ABS gate valves hard to find in 2"?

    Should I go another route?
    Last edited: Nov 15, 2009
  20. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,605
    Location:
    Cave Creek, Arizona
    installation

    The rubber clamps ARE your unions, and you do not need a gate valve on that installation. I have NEVER used one in a residential installation. They are only USEFUL when there is a long discharge pipe which would be full of water. I also would have connected the pump to the top of the pipe, mainly so that water being used upstairs could NOT flow into the pump if the check valve were malfunctioning.
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