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

Discussion in 'Commercial Plumbing Codes' started by Michael.L, Jun 7, 2018.

  1. Michael.L

    Michael.L Sawhorse

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    I'm laying out the floor plan of a public-access restroom for a small cafe that we'll be 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 was 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 by plumbing the lavatory's drain pipe to empty into the uphill end of the linear 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 linear 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).

    Two questions: would this be code compliant and would this be a good/bad idea (and why)?
     
  2. Sifu

    Sifu Gold Member

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    Not code approved. IPC 301.3
     
  3. Francis Vineyard

    Francis Vineyard Sawhorse

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    In the first place I would not require a trap primer where maintenance is likely to prevent loss of seal.

    Also may want to check beginning with the 2015 IPC approved barrier type seals are permitted for floor drains.
     
    #3 Francis Vineyard, Jun 7, 2018
    Last edited: Jun 7, 2018
  4. Michael.L

    Michael.L Sawhorse

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    So I wonder how trap primer lavatory tailpieces get past this requirement:
    Since a trap primer tailpiece bypasses some of the liquid waste into the floor drain, it seems to constitute a non-compliant indirect connection.

    But then there's this exception to 301.3:
    So there is an exception for gray water. Floor drains are not specifically mentioned, yet I fail to see how "flushing" a linear floor drain with gray water is any different than flushing a water closet or urinal.
     
  5. Michael.L

    Michael.L Sawhorse

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    I'm not sure what you mean by this with respect to my original question. Could you elaborate?

    I am familiar with TSPDs and will be using them in the kitchen. But my idea for the restroom is to have a frequently flushed floor drain to wash away unpleasantness like urine that "missed the urinal." What I'm proposing is functionally no different than a lavatory tailpiece with a trap primer tap, except that it uses the entire gray water stream, instead of just a fraction of it. In my mind, it's a "green" solution and far better than trap primers that use clean potable water.
     
  6. Francis Vineyard

    Francis Vineyard Sawhorse

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    Examples of floor drains that may require to have trap primers would be in utility rooms to receive discharge from evaporator condensation or water heater and boiler TPR.
    If the facility has a routine maintenance to monitor the trap seal then I would not require the primer. This includes drains in areas where occupants or tenants will seek remedy of a persistent odor.
     
  7. Michael.L

    Michael.L Sawhorse

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    I understand now. Thank you for clarifying.
     
  8. Sleepy

    Sleepy Active Member

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    I don't know much about plumbing system requirements. But there is a distinction between "direct" connections and "indirect" connections. It looks like the relevant passage in IPC says "directly connected" which might prohibit the indirect scheme you have in mind. For the trap primer tail pieces it may be that the little diverter is actually directly connected to a drain trap, and thus satisfies the requirement to be "directly connected". I'm not sure that is the correct answer but it's at least one way to think about it.
     
  9. ADAguy

    ADAguy Sawhorse

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    ML you have hit on a persistent issue with urinals, especially the waterless variety. Heavy streams tend to bounce back leaving a mess on the floor. This wasn't an issue with the old fashioned full height urinals but it is today. Thoughts?
     
  10. Michael.L

    Michael.L Sawhorse

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    There's certainly the possibility of backsplash outside the urinal, although I think most of the backsplash is still contained within the walls of the urinal. The main problem with waterless (and ultra-low flow) urinals is that the backsplash is not washed off the walls of the urinal, so the urinal gets smelly, dirty, and disgusting if not cleaned frequently. But that's whole 'nother discussion.

    Based on my observations as a man, the majority of the urine on the floor below a urinal is from men being unable to keep their urine stream on target. That and men dribbling/dripping onto the floor at the end of their delivery. I recently read an interesting post about this on some plumbing forum where a guy mentioned that a lot of men have such a large beer gut that they can't actually see where their pecker is aiming when they urinate, thus resulting in a lot of missed targets. That person wrote that he came to this realization while he was dressed in a Santa costume and suddenly found he had the same problem. As for the post-delivery dribbling/dripping, that's because many (most?) men stand too far back from the urinal and because so many urinals are rather poorly designed. Waterless and ultra-low flow urinals will only exacerbate this behavioral problem as men will stand even farther back to avoid the backsplash that's more common with these types of urinals.

    Back to my original topic. I want a way to keep the mess under and around the urinal to a minimum, especially as this urinal will be in a single unisex restroom. At the very least, I will put a standard round floor drain under the leading edge of the urinal, where most of the urine spillage occurs. In my research, I've seen some restroom designs that have a large square grate in the floor where the customer stands at the urinal. That's probably a great idea for a bar, but would be overkill, unattractive, and IMO rather off-putting in our small cafe. I think the linear drain along the back wall, with a gentle floor slope from the front wall to the back wall, would be the most aesthetic design, while also being very functional without being overly obtrusive. It would certainly be less obvious than a large square drain directly under the urinal, or even a standard round floor drain. The trade-off is that the urine would have to drain farther across the floor under the urinal to reach the drain. But the floor could be hosed down as needed, which would be simpler with a linear floor drain along the back wall, than with a single point drain somewhere in the middle of the floor.

    I would still argue that allowing the lavatory drain completely into the linear drain trough (via the lavatory's drain pipe entering the trough at the uphill end) would be permissible based on a common sense interpretation of the code. It would certainly be a good use of the lavatory's gray water, and I cannot see any downside to this kind of installation. From a maintenance point-of-view, it would be superior to the tailpiece with a trap priming tap, because the tiny diameter of the tap and primer pipeline would be far more prone to obstruction. But I doubt the building inspector would be as open-minded about my idea since it's obviously not an accepted practice. Yet.
     
    Sleepy likes this.
  11. north star

    north star Sawhorse

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    @ ~ @

    There are the Stall type Urinals:

    [​IMG] [​IMG]


    @ ~ @
     
  12. Michael.L

    Michael.L Sawhorse

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    From my experience, stall type urinals seem to get even more urine deposited on the floor. I'm not sure if this is because of where such urinals are typically encountered (bars and gas stations), or if it's again a behavioral issue (perhaps men stand farther from them and try shooting at the drain in the floor, rather than at the back wall). In any case, our restroom will be very low traffic, so I don't expect it to ever get too messy or require stall type urinals. Although that first photo NorthStar posted is like a work of art. And that copper Wye fitting is amazing. All that polished copper piping reminds me of my Navy days.

    This is the urinal I've selected for installing in our restroom:

    [​IMG]
     

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