Water Supply Line Crossing Under Sewer Line

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Zane Bridgers

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Hey folks,

Had a question come up about the main water supply line crossing below the main sewer line. The situation is as follows:

Sewer line to septic is 3" PVC @ 18" depth coming through the foundation. Water supply line is 1 1/4 250 PSI Poly @ 5' depth and crosses under the sewer at ~45* angle. Is this permitted as per the 2012 UPC/IRC?

Is it acceptable to sleeve the poly in 2" Sched 4o PVC with some nice gentle 1/8 bends to bring it under the foundation and up through the slab? Should it be sealed with silicone etc. at both ends of the sleeve?

Final question is do we need an open trench inspection of where the water line enters under the foundation or can we backfill and compact as long as all DWV pipes are visible for the pressure test/rough in inspection?

Cheers!
 

Zane Bridgers

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Just to answer my own question in case anyone comes across this. Talked to the chief mechanical inspector for our area today.

Here in northern NM, the sewer must cross at least a foot above the water line, and the water line must be marked with blue caution tape. It does not need to be encased in concrete as in some areas.

A PVC sleeve is permitted, but electrical conduit is not. 2" was too tight for 1-1/4" poly, so we went to 3" with two 45's as a sleeve. The sleeve is not required, we just happen to need it for our circumstance.

We do need an open trench inspection of the water line (to check depth, type of pipe, ratings etc.), and it is technically a separate inspection from the DWV rough in inspection.
 

Terry

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Thanks for the update on that. I wasn't sure what it would have been for your area, but where it's shallow hear, 24" of cover, they also want the line higher than the sewer.
 
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