Today Dean installed the supply plumbing for the main floor bathroom tub. The tub spout will be mounted to the wall (not the tub) and we'll have a hand shower (a shower head and handle mounted to a hose) for rinsing, um, whatever one may feel like rinsing.
The "last inch" of plumbing throughout the house is copper, but the long runs are Wirsbo Aquapex, which is a brand of PEX (high-density polyethylene) supply line tubing. This kind of plumbing is easy to work with because it's flexible and it installs quickly. It's also resistant to damage caused by freezing. The tubing simply expands and then when the ice melts it collapses back to its original shape. That kind of malleability is good for high pressure points, too. Fine Homebuilding did an unofficial test last year and tested a bunch of different PEX configurations under pressure. Their tests consistently pumped about 900 PSI into the tubes before they burst. Considering water comes in from the street between 40 and 80 PSI (ours measures at 65 PSI), there's a lot of headroom before it'll blow.
Plastic plumbing got a bad rap in the 60s and 70s due to faulty materials and joint leak problems. It's taken a long time for its reputation to recover, and some plumbers still refuse to use it. Just like with copper plumbing, it's important to make sure the joints are good. When the city inspectors come through, they'll apply high pressure to the supply lines and do a gravity leak test on the drains before they pass the installation.
