Does Bottled Water Ever Expire?

Allow us to paint a scenario. You open a bottle of water and just when that refreshing H₂O is about to hit your lips, your buddy yells, "Stop, that water's expired!" Pfft, what a fool, you think. Water can't go bad... or can it? Suddenly you're questioning everything you ever knew.

No, it turns out water cannot expire. But if it can't expire or go bad, why even stamp an expiration date on a product that will stay fresh until the end of time? Well, this expiration date isn't some scheme cooked up by dubious bottled water marketing executives. The expiration date is actually less about the water and more about the bottle itself. Add this to the list of things you thought about expiration dates that were wrong...

At one time, bottled water companies were required to put those dates on the bottles because it was being consumed by the public (via LiveScience). In 2019, though, the FDA scratched that requirement and said bottled water didn't have a shelf life if unopened (via Consumer Reports). One reason that companies may still stamp a date on their bottles is simply to track their stock rotation. 

Though there has been concern about microplastics leeching into into the water, chemist Sheri Mason told Consumer Reports, "To our knowledge, there is no data with regard to increased shedding of plastics from water bottles due to the influence of time." 

Heat, however, can weaken a plastic bottle's chemical compounds relatively quickly and allow them to seep into the contents inside, which could lead to potential health risks. So if you buy a case of bottled water and forget about it in your car trunk for the entire month of August, should you be concerned? A 2014 study found that only one of four water bottle brands tested showed exceeded limits of antimony (a silvery metal and potential carcinogen) but that the levels were still far below the FDA's health-based regulation limit. 

While water from a bottle stored in a hot car trunk may not pose much danger if ingested once, if you allow your bottled water to sit in the sun long enough, algae or mold may begin to grow. Gross. 

While your bottled water may not necessarily expire, once you open it, the water becomes susceptible to the elements if not resealed. Lifehacker explains that water exposed overnight is going to taste a little off from when you first poured it if nothing is protecting it. Your water hasn't expired, but it has been exposed to oxygen and dust that can cause it to be slightly more acidic and not as fresh tasting. If you want your bottled water to taste fresh for four to six days after opening it, make sure you put the lid back on and store it in the fridge (via Still Tasty). 

As for where you store your bottled water? Avoid placing it near cleaning chemicals, pesticides, or other toxic products (via NSF). Then again, even though it doesn't expire, there are plenty of reasons you might want to skip buying bottled water altogether.