Originally Posted by featherbedder
This a little off of plumbing on A.S. but good swim pool installers use pvc in inground pools, they have heat box can bend pvc to fit without els etc. winter cold does not effect pvc in frozen ground. My opinion I would not worry about cold with pvc. Bill
Boring engineering stuff follows. Read at your own risk!
Plastic Pipe Institute (PPI) identifies the allowable temperature range for various types of plastic pipe in "non-pressure" applications. Because of the pressure regulator in your Airstream, the water pressure will be low enough for these values to be relatively accurate:
ABS 0°F to 180°F
Polyethelene -40°F to 180°F
PEX -30°F to 210°F
PVC 0°F to 150°F
CPVC 0°F to 210°F
Polybutylene 0°F to 210°F
PPI also notes that for high-temperature applications, all plastic pipe materials have to be supported at closer intervals, up to continuously supported (laid in a full-length trough) near the high end of the temperature range. So put your pipe supports closer together for your hot-water piping to keep it from sagging, and try to avoid using PVC for hot-water piping.
If you live in the Great White North™ your best bet is Polyethelene or PEX. Ditto if you plan to do winter camping at all. In more temperate climes where the temperature doesn't drop to negative digits, any plastic pipe material will work, though you may have to avoid moving your Airstream during the winter due to embrittlement of the plastic.
Note that, just because a particular plastic material may be good to sub-freezing temperatures, that does not apply to ice forming in the pipes! You still need to winterize, even with Polyethelene or PEX.