Can Bottled Water Go Bad?

The four major bottled water brands—Dasani, Aquafina, Glacéau Smart Water, and Nestlé Pure Life—each generate $1 billion in annual sales in the U.S. alone. That’s a huge amount of bottled water! While most people consume it quickly, some people store it for emergencies or to take advantage of a good deal.

But is it a bad idea to keep bottled water for months or even years? You may have noticed a "sell-by" or "best-by" date on your water bottle, but what does that actually mean? Can something as natural as water actually expire?

Why Bottled Water Has an Expiration Date

The issue with expiration isn't the water itself—H₂O doesn’t contain sugar, proteins, or preservatives that typically lead to spoilage. The real culprit is the packaging.

Most bottled water (over 97%) is sold in plastic containers. These plastic bottles are slightly porous, which means they could allow air and gases—like those from household chemicals or petroleum-based products—to affect the taste and smell of the water, as noted by the International Bottled Water Association (IBWA). It’s important to mention that some water brands use higher-quality plastic, which can extend the shelf life but comes at a higher price.

Interestingly, the U.S. Food and Drug Administration (FDA) doesn't require bottled water manufacturers to include an expiration date, as the agency states that the product has an indefinite shelf life. In fact, the FDA only mandates "best by" or "use by" dates for infant formula, not other products. These dates are typically set by manufacturers and might not necessarily indicate a decline in quality after the date has passed. The International Bottled Water Association website explains, "Some companies still place date-based lot codes on bottled water containers, which distribution and retail points typically use to assist in managing stock rotation." If you spot a date on a bottle of water, it usually indicates a two-year expiration period marked as "best by," but this doesn’t mean the water will automatically make you sick if the date has passed.

However, there are still some considerations to keep in mind when consuming "old" bottled water.

Proper Storage is Crucial for Preserving Bottled Water

While bottled water may be safe to drink past its "best by" date, much depends on how it has been stored. Some studies suggest that antimony, a chemical found in many plastic bottles, can leach into the water if it's stored in high temperatures for extended periods. However, the increased antimony levels are unlikely to harm someone who drinks that water.

The IBWA website advises that bottled water should ideally be kept at room temperature or cooler, and stored away from direct sunlight and household chemicals. Both excessive heat and sunlight can cause mold or algae to form in the water, the website notes, which can result in a rather unpleasant drinking experience.

Leaving a case of water in your car over the summer is probably not the best idea. While bottled water can tolerate some exposure to heat (which likely occurred during the shipping and storage processes), it will last longer and taste fresher when stored correctly from the moment you buy it.