S.O.P. here for copper out the wall from inside the dwelling/building. Residential is pretty much 100% poly pipe, pulled; never seen PVC on a residential system here. Maybe Greenmonster has on the large estates he works on out east from me in the Hamptons? Big commercial is often PVC, installed by the plumbing subs or spec'd on the plans. Sometimes they use poly to each head/zone after a remote manifold. Then they bury all kinds of carrpy rock n debris ladden filler "dirt" on top of everything. Add one inch of mediocre topsoil then lay sod. Sometimes I have seen 200 psi thick walled 2" or 1.5" poly used as a mainline all around an apartment/condo/townhouse complex. If your conditions allow it, pulling poly is a bazzilion times faster and less damaging to existing sod compared to trenching PVC. ::begin Holy War:: Belt and suspenders. "There's no weeping in valve boxes".