The bottled water expiration date is not exactly because the water will go bad, instead it's the bottle itself. After some time, the plastic starts to break down and leech into the water. Storing the bottles somewhere cool and dark will slow that process down though.
That being said, if the seal isn't broken, it's not going to make you sick even if it's well past the expiration date.
This is also a pro tip for cutting chicken breast into cubes - it's way easier to do while it's still partially frozen.