Rough DWV plumbing water/air test

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IAm_Not_Lost

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Hello,
I was hoping for some reassurance on some under slab plumbing. I am currently building a home and I am at the stage of just finishing the above ground rough DWV. The under slab section was done with the help of a commercial plumber who took the job on the side. I’m in Arizona and when we were installing last summer the temps were 100+ and windy. We had a few spots that were leaking and needed to be replaced. I was not there for the repairs and the water column test - unable due to work obligations - but he told me it all went well and obviously the inspector passed it.
Fast forward to now and I’ve just finished the above ground portion and filled everything up. Had a couple small weeping joints that I repaired and now everything above ground looks good, no leaks, and I went over every joint with a fined tooth comb. My concern is that the water very very very slowly gets lower. Over a period of about 30 minutes I notice maybe a drop of about an 1/16”-1/8” of water from the top of my 3” vent. I havent let it sit for 24 hours as of yet because the site is quite a distance away and I didnt want to leave it for days like that.
I did also rig up an air test using a 15lb pressure gauge that you can find at Home Depot for testing gas lines, and the system did meet the 5lb for 15 minute test, but after about 30 minutes there was an almost imperceptible dip of the needle, not even a full lines worth, but there nonetheless.
Am I overthinking this? Or should I be concerned there is a minor seep under the slab? Sorry for the lengthy post. Your responses are appreciated.
 

James Henry

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If you filled the system with water with on all of the up right pipes capped off, the water may have compressed some of the air that was trapped in the vertical sections of pipe causing the water level drop. fill the system up with water again, if the level doesn't drop after 15 minutes, walk away.
 

IAm_Not_Lost

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If you filled the system with water with on all of the up right pipes capped off, the water may have compressed some of the air that was trapped in the vertical sections of pipe causing the water level drop. fill the system up with water again, if the level doesn't drop after 15 minutes, walk away.

Yeah I was wondering about that after the air test seemed to pass ok (not my preferred method, obviously prefer water, just much more difficult where I am at). I may just uncap all the first floor upright drains and just fill it up to the top of those (giving it about 4-5 ft of water height) and just make sure that doesn’t drop. Thanks for the reply.
 

Soonermagic22

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Hello,
I was hoping for some reassurance on some under slab plumbing. I am currently building a home and I am at the stage of just finishing the above ground rough DWV. The under slab section was done with the help of a commercial plumber who took the job on the side. I’m in Arizona and when we were installing last summer the temps were 100+ and windy. We had a few spots that were leaking and needed to be replaced. I was not there for the repairs and the water column test - unable due to work obligations - but he told me it all went well and obviously the inspector passed it.
Fast forward to now and I’ve just finished the above ground portion and filled everything up. Had a couple small weeping joints that I repaired and now everything above ground looks good, no leaks, and I went over every joint with a fined tooth comb. My concern is that the water very very very slowly gets lower. Over a period of about 30 minutes I notice maybe a drop of about an 1/16”-1/8” of water from the top of my 3” vent. I havent let it sit for 24 hours as of yet because the site is quite a distance away and I didnt want to leave it for days like that.
I did also rig up an air test using a 15lb pressure gauge that you can find at Home Depot for testing gas lines, and the system did meet the 5lb for 15 minute test, but after about 30 minutes there was an almost imperceptible dip of the needle, not even a full lines worth, but there nonetheless.
Am I overthinking this? Or should I be concerned there is a minor seep under the slab? Sorry for the lengthy post. Your responses are appreciated.
Did you ever find out if 3/4 inch drop over 24 hour period is OK?
 
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