Looking for a valve to stop backflow from a dry well


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Old 08-14-18, 11:08 AM
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Looking for a valve to stop backflow from a dry well

Hi,

The short version is this: I'm looking for a valve that allows outflow from a water softener into a dry well, but will block a high water table from flowing back from the dry well.

The long version is this: I have a water filtration system (softener, acid neutralizer, and rust remover). They all regenerate and drain their backwash into a dry well. But when the water table is high, the backwash backs up into the house and spills onto the floor.

So my idea is to put a T in the pipe that goes to the dry well. Have that T go up, against gravity, and then feed into the septic system's holding tank which is just a few feet away (not into the septic tank itself). So backwash will normally go to the dry well, but when the water table is high and the dry well is full, the backwash will go up the T and flow into the holding tank, where it'll get pumped up to the drain field.

The one problem is that if the water table goes above the T, ground water will flow from the dry well into the holding tank and my pump will be trying to drain the entire yard. So I want a valve between the T and dry well. When the water table is low, backwash will be able to flow through the valve and into the dry well. When the water table is high, ground water will come into the dry well and flow back through the pipe, but the valve will be pushed closed and the ground water won't flow into the holding tank.

I've discussed this with my septic guy and he says it sounds good in theory but he has his doubts that it will work in practice. He can't really specify what he thinks will go wrong, but he's skeptical. And so I turn to the folks here.

Is there a valve on the market that would work here? Is there any reason to doubt it would work?

Thank you,
Bob
 
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Old 08-14-18, 11:57 AM
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I have an Acid Neutralizer Tank myself and the backwash goes to a drain in my basement connected to my private storm water system. I remember reading a lot about where and how to route backwash when I installed the tank (but I forgot most of it –lol). But I don’t see how it could ever be legal (or desirable) to have a connection from the potable water system to a septic holding tank.

But maybe I misunderstand your concept.
 
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Old 08-14-18, 12:18 PM
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I would install a check valve (backflow preventer) in the discharge line from your filtration system. Even if the water table rises and your dry well is under water the higher pressure should force the reject water out with the check valve preventing back flow into the house.
 
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Old 08-15-18, 02:03 AM
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But I donít see how it could ever be legal (or desirable) to have a connection from the potable water system to a septic holding tank.
There is noting illegal about connecting the discharge from a softener to a septic system and if you do some googling there is a lot of comments regarding the effect of doing so.

I've done it myself, I personally do not believe it is the worst thing you can put into a septic tank but try to avoid adding anything to a field that doesn't need to be there!
 
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Old 08-15-18, 07:28 AM
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Marq1 what I mean is that as far as I know for sanitation purposes there has to be an air gap between the backwash drain line(s) from the tank(s) and the sewerage system – in this case, the septic system. If I understand the plan there is no air gap and the house backwash water pressure is pushing the water all the way out and up into the septic holding tank if the dry well is full.

So that would mean there is an unbroken connection from the tanks being backwashed (the potable water system) all the way to the septic holding tank. I think that would be wrong, even if a check valve is used, but I’m not 100% sure. It’s OK to dump the backwash water into the septic system but you can’t have a direct connection – you need the air gap. I believe that’s true.

I think what I’m trying to say is that according to the plan the setup would be what is known as a cross-connection (potable water x septic system), which is illegal. I think … lol.
 
 

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