Reverse Osmosis Saddle Drain on Vent?

Discussion in 'IPC Plumbing Code Questions' started by sydflash, Feb 2, 2017.

  1. sydflash

    sydflash Member

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    MA
    This question concerns a NH plumbing issue.

    I would like to install a Drain Saddle for a Reverse Osmosis System on a vent pipe.

    The code says "The discharge from a reverse osmosis drinking water treatment unit shall enter the drainage system through an air gap...".

    I think this means I can drain the RO waste into the vent pipe, but I would like other more learned opinions.

    I get a bit confused, because I don't think the RO system has a "flood level rim".

    I don't know if it matters, but the system is installed in the basement.
     
  2. sydflash

    sydflash Member

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    hmm.. perhaps it would need to be installed above the highest flood level rim of the highest fixture connected to the vent?
     
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  4. Reach4

    Reach4 Well-Known Member

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    It definitely does not mean that.

    Can you put the drain hose exit above the laundry sink or a floor drain?

    A flood level is where the water goes over the top and runs out to the floor if the sewer backs up. For a sink, it would be the rim of the sink.
     
  5. sydflash

    sydflash Member

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    unfortunately, I have neither.
     
  6. Reach4

    Reach4 Well-Known Member

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    Is there a washing machine down there? What happens if water gets on the basement floor? What happens if the water heater temperature&pressure relief valve emits water?

    Is there a condensate drain for an air conditioner or high efficiency furnace down there?

    It is possible to run the drain to a higher floor, but not without further factors considered.
     
    Last edited: Feb 2, 2017
  7. sydflash

    sydflash Member

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    Yes, there is a washing machine and its waste water line runs up to a drum trap. It's at least 25 ft away from the RO system.
     

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  8. Reach4

    Reach4 Well-Known Member

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    You could run that line to the PVC pipe on top of that standpipe. You could work out your own, or you could buy a fitting made for the purpose that would sit up there.

    I am not that familiar with RO units, but I think the drain could go up under the sink where you are running the RO water. Some RO units have pumps to increase the pressure. Even if you did not have that, I think the throughput would be a function of the water pressure coming in to the backpressure of the drain coming out. Yes, there would be some pressure head on the raised drain hose, but the incoming water pressure would be higher by the same amount. So based on logic, but not experience, I predict that would be fine in most cases.

    Now if you do put in an air gap up at the sink, where does that go? Many RO faucets have a built in air gap. The purpose is to spit water into the sink if the drain gets blocked, rather than risking a clogged drain line from feeding back to the RO unit. They also have separate units made to go into an extra hole in the sink.
     
  9. sydflash

    sydflash Member

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    The air-gap requirement is a real pain in the ass, given the RO System has safeguards against reverse flow.

    I currently have the RO drain plumbed into the the kitchen sink drain, but it is loud when it discharges as it trickles into the water in the p-trap. I tried a different configuration - adding some 45 degree slip elbows, but there were issues.

    As the vent was accessible in the basement it would have been the easiest fix to discharge into that, but I can see now that is not a good idea.

    I may just buy this flexible drain and a new RO Faucet with a built in Airgap.
     

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  10. Reach4

    Reach4 Well-Known Member

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    I am not a plumber, but I still would not do that. Flex lines are said to be more likely to clog.

    So you have the option to run (1/2 inch for example) drain tubing to the WM area. You don't have to maintain a steady slope. That sounds cheap and easy, and solves the sound worry.

    Is it time to add some plumbing to the basement? Utility sink? Extra bathroom?

    Air gaps have not been required that long. Your current standpipe plumbing is not to code anyway, with your unbanded rubber couplings.

    Do you have a disposal, and dishwasher feeding into the disposal? You might post a photo of your undersink area.
     
    Last edited: Feb 2, 2017
  11. sydflash

    sydflash Member

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    Why would the flex drain and the RO faucet be wrong?

    I have had plans to put in a laundry sink for about 15 years now ;)
     
  12. sydflash

    sydflash Member

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    found this basic diagram for how the Airgap faucet is done... red is waste water drain
     

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  13. sydflash

    sydflash Member

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    Oh great... found out Airgap faucets make a gurgling noise.
     
  14. Reach4

    Reach4 Well-Known Member

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    Here is something else to add to your options: a "zero-waste" RO system. Watts even offers a retrofit kit. It pumps the drain water into the hot water line. It all stays potable. No air gap needed. It is usually used for water saving.

    While you are planning, how about a humidifier for the furnace? The preference today is normally to have that have a drain also. The water that does not evaporate, goes to a drain. That carries minerals with it, so the pad etc does not lime up nearly as quickly.
     

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