First, does Potable Aqua have a "shelf life"? If so, what is it?

I've only got one bottle (I know, I need more...:-) & I dated it 7/99, so it's 3-1/2 years old. It's never been opened. I can find nothing on the label indicating expiration.

Second, does using PA (according to the directions) have any effect on the hydration bladders (polyethelene?) such as those by Camelbak, Hydrastorm, or Platypus? How about Nalgene bottles?

Appreciate any feedback.

Thanks.

David