Since Spring is supposedly here (although it's sleeting this morning), I'm considering my long term storage of water in my truck to be complete, with great results.

Last summer, I bought a case of .5 liter bottles of water to put in my truck. I left them there, taking one out every couple of weeks through the winter to see how they fared. Of course they had frozen solid, but when thawed, showed no signs of weakened plastic or leaking. Now the remainder are all thawed, and no leaking occurred.

A couple of observations.
When they froze, the water expanded of course, but there is just enough air space in the bottle to allow for this expansion without rupturing. However, you can't stand the bottle up, because the bottom becomes rounded. Also, when you open it up, it tends to spray a bit of moisture out.
Now that they are thawed, the ones that fell over on their sides have contracted, I guess due to the freeze/thaw, but not the ones that stayed upright through the process.

So, no problem carrying emergency water through the winter.