No, of course not packed water does not have an expiry date. Water does not expire it’s the bottle that expires. Every bottle from simple plastic to a good quality Tupperware expires.
There are several reasons why water bottles come with an expiration date. The main one is government bureaucracy: Water is a consumable food product, and as such, it is subject to laws requiring expiration dates on all consumables.
The reason why packaged drinking water has an expiry date is that the plastic that has been used will start degrading after a certain amount of time. And yes, even the high-quality plastic will degrade after some time.
If left unwashed, any water bottle can harbor microbes—a 2002 study in the Canadian Journal of Public Health found that 65 percent of elementary students’ personal water bottles contained bacteria levels that exceeded health guidelines, for example. But disposable water bottles are particularly hospitable to them. That’s because whereas reusable bottles are designed to hold up to repeated refillings, disposable bottles tend to break down—and that leaves room for bacteria to camp out.
Stainless steel water has a great advantage over plastic water bottles, they keep water cold/warm and also does not allow bacteria’s to grow inside them.
How long can you keep your water open? Not long, Studies believe that keeping water out for long creates a chemical reaction with the air and might turn them acidic in nature. Also, it becomes home to many bacterias.
[Photo credit:By Taken byfir0002 | flagstaffotos.com.auCanon 20D + Tamron 28-75mm f/2.8 – Own work, GFDL 1.2, https://commons.wikimedia.org/w/index.php?curid=729941%5D