Can a lavatory in a commercial restroom empty into a floor drain?

Discussion in 'Plumbing Code Questions' started by mliu, Jun 5, 2018.

  1. mliu

    mliu Member

    Feb 7, 2007
    I'm laying out a public restroom for a small cafe that we're building. I want to have a floor drain for washing down the floor, and I've been considering installing a linear drain along the back wall (which is also the wet wall with a hung toilet, urinal, and lavatory). I got to thinking about trap primers and I know there are tailpieces that can be installed in the lavatory drain to divert some of the wastewater into the floor drain to keep its trap primed.

    That got me wondering: why not just divert all the water from the lavatory into the floor drain? If I do install a linear drain, it will be almost 10 feet long, so the additional water flow would help keep the drain washed down throughout the day (particularly useful in a commercial restroom where some guys tend to put as much pee on the floor as they do into the urinal).
  2. WorthFlorida

    WorthFlorida Broad-Wing Hawk

    Oct 28, 2009
    Orlando, Florida
    It be very easy for the wastewater to back up on the floor all the time. A no no and it can easily cause a slippery floor condition, something insurance companies don't like. Also you then be having waster water going through two traps. Just not code.
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  4. Terry

    Terry Administrator Staff Member

    Aug 17, 2004
    Bothell, Washington
    I don't see any inspector allowing lavs to drain to a floor drain.
    What I do see, is a 1/2" line to prime the trap, mostly with a shutoff below the lav faucet supplying the trap primer, exposed so it can be installed and repaired.

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