I have about 37m of 1/2" plastic water line layed from the house to the back of the garage. Use it for power washing cars & trucks. Summer only. It's about 18 years old. Bought it at a Lowes type place. Freeze thaw stable. I blow it out with my 5hp compressor. Mine is above ground, but I'd just put yours a couple inches underground and not worry about it. You could burry it with a shovel in a couple hours. All you want to do is protect the water line from damage, not ensure you have a winter supply source. Unless your wanting to supply a grow op in the back 40.
