Originally Posted by younger-plumber
I have met a plumber who tells me stories of how they put 3/4" px pipe in the ground for main lines...is that legal? or safe? just curious because i was always taught poly and pvc...
I use pex for water services and in-building underslab lines routinely. Pex IS polyethelyne - basically it's just cooked a different way to cross-link it, and died a different color. Don't tell anyone I told you this, but in a pinch you can crimp a pex ring and fitting on black poly tube, providing it's the right grade (wall thickness). Inspectors would hate that though, so don't do it.
For 1/2" in-house underslab waterpipes I first run 1" utility grade poly and attach both ends. Then I push 1/2" pex (I use up all my heating loop scraps for this) through and then tape up the ends. Don't try it on sleeve much longer than about 20' - 25' as the friction gets bad enough at that length that you can't push that "string" any further.
Here's an example. Three lines - you can see two of them coming up in the background in the laundry - the other comes up at the toilet you can just barely see at the near right.
For water services I only sleeve going through concrete walls/footings and where it comes through the slab, again with utility grade poly-e.
I've seen pex survive being run through crushed stone gravel. It's tough stuff. I'd prefer to have some sand around mine though.