I boiled some water, then poured it into a Dannon water jug.  It's
similar to a regular plastic bottle, but much larger, and it is
recycling number is 1.  Concerns are that it's not labeled as
microwave safe, nor is it made out of a sturdy material .  The plastic
water bottle shrunk dramatically in size (80% of original), so I'm
assuming there is less plastic material than we started with.  Looking
in the bottle, I can't visually see any signs of impurities.  I have
the following questions:

1) Where did the extra plastic material go?  Did it vaporize, go into
the water, or just become more dense?   How is it different from
putting a water bottle into a pot of boiling water?  If the
temperature dips back below the melting point of plastic, why does it
not reform?

2) Is the water safe to drink after the bottle has been warped?  What
about if reboiled?

3)  I've read about microwaving plastics,
(http://answers.google.com/answers/threadview?id=286529 is useful). 
How is boiled water warping plastic different/similar to microwaving
it?


Thanks for all your time.