Can I Tie A Sink Drain Into A Floor Drain Vent Line?

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by Cedar, Aug 19, 2009.

  1. Cedar

    Cedar New Member

    Messages:
    9
    I would like to put a utility sink in a particular location in my basement. There is a floor drain near the planned sink location. The vent pipe for the floor drain runs up a nearby interior wall a couple of feet from where I would like to place the sink. The drain connects to the septic system.

    Can I safely tee into the vent stack and connect the sink's trap to that point?

    Thank you.
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,313
    Location:
    New England
    Generally, once you make a vent a drain, it no longer functions as a vent, so no. You'd have to tie into the drain line before the vent take-off fitting. You could connect to that vent above the flood plane of the new sink so you don't have to run a new vent line, though.
  3. Cedar

    Cedar New Member

    Messages:
    9
    The vent take off fitting is embedded in the basement floor. I was hoping what I would like to do constitutes a wet vent.
  4. Herk

    Herk Plumber

    Messages:
    547
    Location:
    S.E. Idaho
    You're in luck! It does constitute a wet vent.

    That's what's wrong with it.

    Whether you can do what you want to do depends upon your local code and how it is enforced.

    For example: in the Uniform Plumbing Code, you can wet vent a toilet with a basin drain, but the required vent (2") has to be raised to the next pipe size when you do (3" assuming there is no 2-1/2" pipe available).
  5. nhmaster

    nhmaster Master Plumber

    Messages:
    3,189
    Location:
    S. Maine
    Well, yea but that can be said for probably 90% of wrong plumbing.

    You can only wet vent bathroom groups (fixtures) no kitchen sinks, laundry trays, washing machines etc.
  6. FloridaOrange

    FloridaOrange Plumbing Designer

    Messages:
    1,317
    Location:
    SW Florida
    I am very familiar with that rule but not the reasoning behind it, any insight? It makes it a pain when trying to add a drinking fountain to a small commercial space.
  7. Cass

    Cass Plumber

    Messages:
    5,980
    Location:
    Ohio
    If what you will be washing down the sink you could just as easily pour down a floor drain then you could install a utility sink and make the drain to the floor indirect...you would be giving your self a sink to splash in and just dumping rinse water down the floor drain...that would also keep it from drying out...if you are dumping any sort of industrial waste...don't do it...
  8. Cedar

    Cedar New Member

    Messages:
    9
    Thanks for the replies.

    The sink will mostly be used for washing up. Nothing will go down the drain that isn't septic system safe. Unfortunately, the floor drain is in the walkway part of the room, a home workshop.
  9. Cedar

    Cedar New Member

    Messages:
    9
    So, if I mount a urinal on the wall next to the sink, it would be OK? :cool: :rolleyes:

    I can just imagine my wife's reaction the first time she ses it. :eek: :D
  10. seaofnames

    seaofnames DIY Senior Member

    Messages:
    162
    Location:
    Mission, BC
    Thats kind of what I was thinking. According to most of the stuff I've seen/worked on, floor drains(especially in bathrooms) are 'emergency' so they aren't accounted for in the total number of fixtures. Obviously, we arent anywhere near the limit of fixtures, so there is always a safety factor, but if it really came down to it...the floor drain is only an emergency drain!

    At least thats how it is here in BC!

    And the usual..it depends on which code you are using or what your inspector says.
  11. nhmaster

    nhmaster Master Plumber

    Messages:
    3,189
    Location:
    S. Maine
    If you use a lav and not a utility sink then , yes, you can wet vent it along with a urinal.
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