Does bottled water expire

Answer 1

Sort of. Although water itself cannot rot or "expire", over time a plastic bottle will leach hydrocarbons into the water (especially if the bottle is exposed to head or light). This will first make the water taste bad, and eventually render it undrinkable. Water bottled in glass will not have these problems.

Answer 2

yes but it would actually take a very long time to become undrinkable. If the bottle is unopened and the water pure it can stay drinkable for many years. The makers of bottled water have to add an expiry date by law, but in reality it's not really needed.