Why does bottled water have expiration dates?

There are expiration dates because it's the bottle that expires, not the water. Plastic contains synthetic estrogen and after a certain amount of time that chemical will begin to seep into the liquid that's in the bottle and it may cause health problems

Bottled waters are clean, but not sterile. Eventually, germs might reproduce in the water, so while it has a long shelf life, it isn't necessarily clean forever.

In fact, some certified mineral and spring waters cannot be legally sterilized. They are clean as they come out of the ground and are bottled that way, but there are always a few germs in the water. When the water is fresh, there are too few germs to matter, but after years sitting on a shelf, they might multiply enough to make the water less than ideal to drink. The reason the water cannot be sterilized is that the government agencies monitoring the water assume that sterilized water has been contaminated, so to prevent companies from hiding contamination, it prohibits sterilization. This isn't as weird as it sounds, since water that comes from deep within the earth is practically germ-free, just like tap water.

All plastic breaks down over time. Light, especially sunlight, aids in this process, as well as the oxygen that is naturally dissolved in the water. As the plastic breaks down, it leeches into the water. This can lead to foul-tasting water (that isn't very good to drink, I might add). Also, considering the cap is plastic, that breaks down as well - possibly causing the water to lose its seal - and possibly adding to the foulness - it allows the oxygen to escape, making the water taste stale.

This is why it's recommended to recycle your plastic water bottles instead of reusing them to hold water - they will continue to break down with your "fresh" water from the tap, and will leech chemicals into that as well.

Plastic's a pretty gross substance - but for the short time your spring water is in the bottle, you should be good to go!

Keys to making sure that your water stays yummy in the bottle: Keep it at a consistant temperature. Keep it in the dark. Don't put anything extremely heavy on top of the bottles.

Enjoy!

Chemicals from plastic bottle

The water eventually absorbs chemicals from its packaging.

i wonder the same thing when i see expiration dates. once i see it i won't drink it. once i tried it and i think it tasted different. (none of my friends thought so though)

Which is why I use filtered water anyway, plus, no trash.