Help + Advice Needed Please! Air Gap Leaking from Backwash Drain Lines

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I live in a very rural area where there are almost zero reliable contractors/plumbers. Almost everyone I’ve hired over the last three years, I’ve had to redo some (or all) of their work. So I’ve relied on forums like this (THANK YOU!) and hundreds of hours of research to try and find decent solutions for projects around our home.

That said, for the last 3 years we’ve been running our water softener and iron filter discharge lines through our sump pump. At one point, a landscaper yanked that discharge line out of the ground so we’ve had the hose strewn across the yard and my husband is over it.

Fast forward to this week, I finally went forward with trying to tie in these discharge lines to our 3” septic drainage line which slopes down throughout our crawl space.

I found an existing 1.5” P-Trap that was already tied into the septic line and thought that would be the perfect spot to work from. I purchased the following and installed as you see pictured linked below

Current Setup Image Linked Here

(1) 1-1/2”S X 1-1/2"S X 1-1/2"S Manifold Wye
(2) SCH40 PVC 1.5” Airgaps
1/2 Inch ID Flex Poly Tubing + Clamps

For reference, I only had 1 of the two drain lines hooked up as I need to purchase more tubing for the 2nd line - the iron filter that was hooked up has a 7 GPM flow during the backwash cycle and is safe for septic systems (50-100 gallons of backwash water 1 to 3 times a week).

Last night it went into regen mode and thankfully I was home and heard water pouring out from inside. I quickly shut off our well, sump pump, and all electrical in our crawl before I could get down there.

Fast forward to today, I decided before troubleshooting further, I wanted to be sure the leaks weren’t coming from my PVC work or an unclamped tube, etc. Everything ran smoothly for the first 8-10 minutes. Then the filter went into a 5 minute “rest mode” - when it started back up to move into the next phase, that’s when it started overflowing from the sides and tops of the Air Gaps. Video linked below.

Air Gap Water Leak Video Linked Here

At this point I’ve just about given up hope that we can tie these into our septic line, but I also thought I could ask all of you experts and DIY’ers out there, if perhaps there’s something else wrong with the current setup?

The only things I’ve deduced that could be the culprit are:

1) I need a 2” P-Trap or different PVC connections/parts to handle the 7 GPM backwash
2) I need a longer standpipe (although I’m about maxed out with the ceiling of our crawl space)
3) No clue beyond 1 or 2

I’m open to any and all suggestions and learnings. I’ve read through these forums and it seems to be common opinion that a saddle tee / clamp at a different spot isn’t a great option which is about the only other thing I can ideate at this point. We’re trying VERY HARD not to have someone dig 4’ into the ground to get our sump discharge hose below the ground (we live in Michigan) as we just had a ton of landscaping done and the yard is finally put back together.

THANK YOU in advance for all your insight and tips and feedback. I am sure I did something wrong and don’t proclaim to be an expert or a know it all - I would gladly hire someone if anyone would actually show up and do the work they say they can do. Haha.


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