I want to know the same thing. I live in MN and we freeze up bad in winters. Is something like a 200psi 1" poly mainline going to be ok? I'm on a well and only get 6GPM and 50PSI static. Was planning zones to have around 6GPM throughput.
Specifically I'm looking at this for the main lines (pipe from PVB to back of the valves)
http://www.menards.com/main/plumbing/rough-plumbing/pipe-tubing-fittings/pipe/polypipe/1-x-300-flex-water-pipe/p-1459373-c-8570.htm
Thanks!