Softener Discharge drain design questions

Discussion in 'Water Softener Forum, Questions and Answers' started by InmatesRunThePlace, Feb 18, 2020.

  1. InmatesRunThePlace

    InmatesRunThePlace New Member

    Nov 10, 2019
    Guys - I've been reading for about 3 hours on the great information from this site and still have questions for this common topic.

    1) Looking to install a softener for my whole house which will be placed in an unfinished space of my basement.
    2) We are on city sewer and the house sewer line exists the foundation wall about 3 feet above the floor in the basement.
    3) There is no plumbing (sinks, floor drains) in the basement besides the sump and sump pump.
    4) All drains from the house run down through the ceiling of the basement out the main sewer line.
    5) The washing machine is on the second story of the house and it is realistically impossible to run anything up there.

    I have access to some drain lines that I can use, create a stand pipe, air gap, p-trap, and use a AAV if needed. My main concern is that this would then become the lowest open point in the sewer line and would result in a "shower" if there was a sewer line restriction. Tree roots, who knows what.

    I don't like the idea of increasing the risk of the shower in the basement, even in unfinished space. What is the problem with using a valve like this on the other side of the p-trap to restrict the flow back into the trap if there is a restriction down the line?

    Any other recommendations to reduce the risk? This might be a show stopper for me in fixing my 20g hardness because I really don't want the increased risk if I can't otherwise work through it.


  2. Reach4

    Reach4 Well-Known Member

    Sep 25, 2013
    You have what is called "overhead sewers". That is good.

    You can run the drain line to the floor above if you like. You could maybe share the washing machine standpipe. Running some PEX thru the walls is usually not that impossible. Some plumbers know how to fish pipe, just as some cable installers and electricians know how to fish wires. Typically that would be originated in the laundry room, and you would drill down through the wall to the basement, where running the line becomes easier.

    You can create a standpipe in the basement with the opening up high -- above ground level. is one prior thread that might inspire you.

    Regarding the idea for a check valve, note that softener drains are supposed to feed through an air gap. That means the drainage will not be pressurized by the time it hits the sewer. Check valves for sewage can leak.
    Last edited: Feb 18, 2020
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  4. HudsonDIY

    HudsonDIY Member

    Jun 19, 2019
    Hudson, Florida USA
    If you aren't comfortable draining into your existing sewer lines you could install a drywell and drain into that. Mine is in the front corner of my garage nowhere near any drain lines and dumps into a drywell installed just outside the garage.
  5. Smooky

    Smooky In the Trades

    Apr 4, 2011
    North Carolina
  6. InmatesRunThePlace

    InmatesRunThePlace New Member

    Nov 10, 2019
    Perfect, thanks guys. I'll think over it a bit and choose the right option.

    Thx for the poisoning the family link. I'm certainly not going to consider skipping the air gap, that was never in my plan. Mostly trying to limit the risk of having raw sewage on my basement floor. :)
  7. Bannerman

    Bannerman Well-Known Member

    Mar 19, 2014
    Ontario, Canada
    If there is ever a blockage in the main drain line exiting the home, effluent will likely discharge from the lowest drain opening within the home such as from a toilet on the floor level directly above the basement level. This has nothing to do with whether or not a softener is installed, but is because of the configuration of the drain lines.

    While any type of water leakage is not desirable anywhere in a home, if given a choice, I think restricting damage to an unfinished basement would be the better option compared to finished living space. Maybe the potentially effected area can be further confined to a basement section that is not used for storage or items that would become damaged.

    If the softener standpipe is located nearby to the sump pump pit, perhaps any unintended discharge will flow into the pit. If the basement is infrequently occupied, to alert of a potential issue, you may wish to consider a moisture alarm sensor on the floor below the standpipe.
    Last edited: Feb 19, 2020
    V Scott likes this.
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