I installed a water softener in a house we just moved into. I did a manual regen to test everything and nothing or at least very little drains past the P Trap and is pouring into the crawl space. I put a studor vent on the P Trap and have an air gap between the discharge hose of the softener and the p trap entry. The p trap is not clogged as it was just installed. Why is this not draining? What did I do wrong?(I know I'm using a pvc fitting on the air gap where it should be abs, this is the only thing that hasn't been glued yet, just haven't been to home depot to get the correct fitting and wanted to test it out first) enter image description here

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  • Putting an open air-gap in a hidden crawl space seems like a very bad idea to me. Nov 6 '20 at 2:01
  • The air gap is per the water softener manufacturers recommendation and is to my understanding to prevent back siphonage if the drain gets backed up, not sure what other options I have.
    – Cody H
    Nov 6 '20 at 2:06
  • You just installed this drain pipe? So, where does it go, what does it connect to, pipe sizes, is the slope correct, the usual sort of basics. You should be able to run a garden hose into that trap and not have it back up (you don't need to regenerate for basic testing of basic function, though you do need to verify that it works at the flow rate the softener dumps, but to start poking the problem, use a hose. Then regenerate once you have it working with the hose.) Not getting the slope correct all the way is a common error.
    – Ecnerwal
    Nov 6 '20 at 2:25
  • I just installed the p trap into an existing 2" drain pipe that runs from the dishwasher and sink in the kitchen to the main 3” pipe about 20 ft away. The sink and dishwasher are not running when this happened. The new p trap is about 10ft from the kitchen sink. The only thing that is new is the p trap, the slope on the 2" drain has not changed and we have no issues with the sink and dishwasher draining. Yes I probably got excited about testing it out and shouldn't have done the regen but it was easier at the time.
    – Cody H
    Nov 6 '20 at 2:46
  • I think you are right about the slope, after looking closer the slope did change a decent amount when I had to cut into the 2" to add the ptrap, and when glued it back the slope is no longer correct.
    – Cody H
    Nov 6 '20 at 3:01

It was the slope, when cutting in the p trap I changed the slope of the existing 2" drain pipe, and caused it to back up. Re-did it and ensured the slope was correct and checked with a hose and a manual regen and all drains fine.

  • Glad you were able to lick it! Mind explaining what a "manual regen" is though? Nov 7 '20 at 3:09
  • Forcing (manually) the water softener to run a regeneration cycle (which it normally does automatically in the middle of the night) which involves the part of the cycle where it uses the drain as it flushes the softener out.
    – Ecnerwal
    Nov 7 '20 at 5:23

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