Backwashing a Manganese / Iron filter to septic

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btPlumber

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I have a minor iron / Manganese problem but no smell or taste issues.
Recent water test:
142 mg/l (ppm) hardness
Iron .071 mg/L
Manganese .095 mg/L

I’ve purchased a Pro-Aqua filter: https://proaquawater.com/collection...l-1e-whole-house-well-water-filtration-system. At this stage I’m not planning to add a water softener. I will start by removing the Mn and Fe first - then do another water test. May consider an electronic descaled at some point to address a bit of water spotting / stains on the fixtures.

I have 2 questions:
1) This is for a 2nd home so our water use is less that a primary residence - we are also semi-empty nesters. I shut the water off when we are not there - to avoid flooding when not there. Since our schedule is irregular I don’t want the filter recharging ever x hours automatically. There is also a “Metered” mode which the instructions say not to use. There is not clear description of what Metered mode is - if it’s based on x gallons, then I think it will solve my problem since no water is flowing when we are not there.

2) Since I’m on septic I’m trying to understand any concerns about backwashing to it. I do not have a softeners or any form of chemical injection - so I don’t think I have the same concerns with softener brine or chlorine etc. Since I’m essentially filtering out what would normally be sent to the septic I don’t think it should be of concern. My septic system has primary and secondary tank - Since the filter is converting the Manganese and Iron to their precipitated forms I would think the particles would settle there before causing any issues in the leach field. I’m in NH so backwashing to the surface would only be practical in the summer - I would like to utilize the water for the yard in the summer - may hook up a diverted for summer use.

All advise / discussion welcome.. thanks
 

Reach4

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I have no clue what media your proposed iron + manganese filter has, but it probably takes 50 to 100 gallons to backwash. So the problem would not be what is in there, but the volume put out in 10 minutes could be a negative. I am not saying that I know there is a problem with such volumes into the septic tank.

The water would be good in the yard in the summer. I would wonder about a method that takes the water outside if it can, but if there is backpressure due to ice, the water would route into a laundry tub or standpipe.

I would lean toward a softener to do the Iron+Mg removal. Those use less backwash water, but you would not want the drainage from that to go to the plants. You would either put in a dry well, or feed to the septic system, or feed that drainage directly into the leach pipes, bypassing the tanks. There are various opinions on that. The dry well would be liked by everybody, if your subsoil is absorbent enough.

I would aid the softener by either using iron-handling salt, or to separately add phosphoric acid (ResCare dispenser), Iron-Out, citric acid powder either mixed into the salt, or for periodic batch cleaning.
 
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btPlumber

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Thanks for your input. Just as the softener water is not good for the plants I would guess it’s not great for septic digestion. Since I’m in a cold climate the top of the drywall would need to be 4 down and would require a penetration in the foundation - that’s going to do a lot of damage to the yard putting that in. My basement is bone dry and I don’t want to compromise that by boring a hole in the foundation below grade. I’m Also not a fan of the added salt in the water and that slimy feeling after a shower in soft water. Our water is visibly perfectly clear and we aren’t concerned about the hardness - just want less rust staining of laundry whites and toilet staining. While 50-100 seems like a lot of water for the system, isn’t it the equivalent of 3-4 showers?
 

oldVermonter

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50-100 gallons is no big deal for a septic tank. Nor is softened or chlorinated water. Neither will cause any digestion problems.

Precipitated - - but suspended - - backwash solids could hypothetically be an issue in your leach field if the quantity was large enough, though very unlikely I suspect. Particles large enough to settle out won't make it past your septic tank, as long as you get it pumped regularly.

If possible, I would do your first flush into the yard, and see what it looks like. My guess is the amount of solids is not a problem in any case.
 

Reach4

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Thanks for your input. Just as the softener water is not good for the plants I would guess it’s not great for septic digestion. Since I’m in a cold climate the top of the drywall would need to be 4 down and would require a penetration in the foundation - that’s going to do a lot of damage to the yard putting that in. My basement is bone dry and I don’t want to compromise that by boring a hole in the foundation below grade. I’m Also not a fan of the added salt in the water and that slimy feeling after a shower in soft water. Our water is visibly perfectly clear and we aren’t concerned about the hardness - just want less rust staining of laundry whites and toilet staining. While 50-100 seems like a lot of water for the system, isn’t it the equivalent of 3-4 showers?
1. I suggest this Google search:
"soap curd" slimy softener

2. https://wqa.org/Portals/0/WQRF/SepticToolkit.pdf
Try this Google search:
septic study softener site:edu

3. I don't think that this all has to be below the frost line, but the line should clear by gravity before the warmer water from the drainage freezes up.

4. I doubt that your leach pipes are below the frost line.
 

btPlumber

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1. I suggest this Google search:
"soap curd" slimy softener

2. https://wqa.org/Portals/0/WQRF/SepticToolkit.pdf
Try this Google search:
septic study softener site:edu

3. I don't think that this all has to be below the frost line, but the line should clear by gravity before the warmer water from the drainage freezes up.

4. I doubt that your leach pipes are below the frost line.
thanks for the links! Interesting comment - I’ll check the typical leach depth here.
 

Mswlogo

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I’m having exactly the same question. Also a vacation property.

The excavator that installed the system pointed out that the new septic design explicitly states that nothing get backwashed into the septic. It’s a 3 bedroom septic.

He said the right solution is a dry well.

I know salt backwash caused problems at our old house. We switched it to potassium and that solved it. We did backwash to septic for 20 years. But it was metered and also empty nesters that live there part time.

I’m concerned about punching a hole through foundation wall too.
 
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