Old Water

Does water get old? Is there an expiration date on bottled water?

It's just a funny thing to think about, considering when I have a glass of water sitting out for days at a time, it somehow tastes different when I go to drink it later. Or if I find a water bottle full of water that's been in there for awhile, it for some reason really grosses me out to even think about drinking it.

But I am sure that there are droplets of water that have been in the ocean for centuries, water that has been trickling down mountains since the beginning of time, maybe even water that has stayed within our bodies since the day we were born. Does that mean water doesn't get old?

I'm not sure really... Just a thought I had today as I stared at a water bottle full of "old" water that's been sitting on my desk for what seems like weeks. What to do you think?