How far do you guys go when piping in CSV's/softeners/filters?

[BeDriven]

I installed a CSV a few months back and slapped it in quick cause I knew I had more changes coming to my softener setup. Well, that day is here and I need to make everything right. I'm pretty particular about my installs (of anything) and would normally solder in copper but it's SO expensive now. What's good standard practice when installing things in a well water system? My well guy glued PVC for everything and left me one test/drain valve by the pressure switch. I see people talk about double union valves and test ports between each filter. How much is too much?

[Cary Austin]

I like PVC but don't really have a preference.  Pex, copper, PVC, poly all work.  Just depends on what pipe you are connecting to.