How long can you keep bottled still water?

January 12, 2026 •

4 min read

Technically, pure water never expires, but the plastic bottle it comes in can degrade over time. Most bottled water companies print a 'best by' date, typically two years from production, to ensure optimal taste and quality, though the water may remain safe far beyond that if stored correctly. However, improper storage can lead to an undesirable taste or even potential contamination.

Quick Summary

The longevity of bottled still water is mainly determined by its container, not the water itself. Proper storage away from heat and sunlight is critical to prevent plastic degradation and maintain quality. Sealed bottles can be safe for years, while opened water should be consumed quickly to avoid contamination.

Key Points

Expiration Date Misconception: The date on a bottled water refers to the quality of the plastic packaging, not the water inside.
Proper Storage is Key: Keep unopened bottled water in a cool, dark place away from direct sunlight, heat, and chemicals to prevent plastic degradation and taste changes.
Limited Lifespan Once Opened: Consume opened bottled water within a few days to avoid potential bacterial contamination from airborne sources or contact with your mouth and hands.
Signs of Degradation: Check for signs like cloudy water, strange odors, or a bad taste before drinking water from older bottles, even if sealed.
Emergency Preparedness: For long-term emergency storage, replace bottled water every couple of years, or as recommended, to ensure the freshest quality.

Does bottled still water truly expire?

This is a common point of confusion for many consumers. The fundamental chemical properties of water (${H_2O}$) mean it does not spoil or expire like organic food products. The expiration or 'best by' date printed on a bottle of still water actually refers to the packaging, not the water itself. Manufacturers include these dates for quality assurance and regulatory purposes.

The real reason for 'best by' dates

Plastic leaching: Over time, particularly when exposed to heat or sunlight, the plastic in the bottle can start to break down. This can cause tiny particles and chemicals to leach into the water, affecting its taste and quality.
Flavor absorption: Plastic is slightly permeable, which means the water inside can absorb odors and flavors from its environment. If stored near household cleaners, chemicals, or gasoline, the water may develop an off-putting taste.
Stock rotation: For many companies, the 'best by' date is simply a tool for managing inventory, ensuring that older stock is sold before newer products.
Regulatory requirements: While the U.S. Food and Drug Administration (FDA) states that bottled water has an unlimited shelf life, some regulations in the past required a date to be printed on all food products.

Proper storage: Key to prolonging freshness

To ensure your bottled still water stays fresh and safe for as long as possible, proper storage is crucial. The key is to protect the water from environmental factors that can cause the plastic to degrade or taint the flavor. The International Bottled Water Association (IBWA) and other health authorities provide clear guidelines.

Where to store bottled water:

Cool, dark location: Store bottles in a pantry, cupboard, or basement where temperatures are stable and they are not exposed to direct sunlight. Heat accelerates the breakdown of plastic, so avoid hot garages or leaving bottles in a car.
Away from chemicals: Keep bottled water away from cleaning supplies, paint thinners, gasoline, and other chemicals. The permeable nature of plastic means the water can absorb the odors and tastes from these substances.
Elevated from the floor: For long-term storage, avoid placing bottles directly on a concrete floor. Place a small platform underneath for air circulation, as concrete can transmit temperature changes and moisture.

Opened vs. unopened bottled water

The shelf life of bottled water changes dramatically once the seal is broken. The moment a bottle is opened, it is exposed to airborne microorganisms and bacteria from the environment and your hands. This is why opened bottled water has a significantly shorter lifespan.

Guidelines for opened water:

Opened bottled water: For an open bottle, it is generally recommended to consume it within a few days, or up to a week if refrigerated. The cool temperature of the refrigerator will slow down bacterial growth. Always recap the bottle tightly to prevent contaminants from getting in.
Opened tap water: Stored tap water also has a limited shelf life. It is best consumed within 24 hours if left at room temperature, as the chlorine that keeps it safe will dissipate over time.

A comparative look at water storage


Feature	Bottled Still Water (Sealed)	Bottled Still Water (Opened)	Tap Water (in glass container)
Primary Concern	Plastic bottle degradation	Bacterial contamination	Bacterial contamination, chlorine dissipation
Optimal Storage	Cool, dark, and away from chemicals	Refrigerated	Refrigerated
Long-Term Safety	Safe for years beyond 'best by' date	Limited, few days to a week	Good for up to 6 months if refrigerated and sealed
Taste/Quality	Can be affected by plastic leaching or odor absorption	Can be affected by bacteria	May taste 'flat' as chlorine evaporates

What to look for when evaluating old bottled water

Before drinking water that has been stored for a long time, use your senses to assess its quality. Even if the 'best by' date has passed, it may still be perfectly safe.

Signs of spoilage:

Appearance: The water should be clear. If it appears cloudy, has discoloration, or you see any floating particles, it is best to discard it.
Smell: If the water has a strange or musty odor, it may have absorbed chemicals from its surroundings or bacteria may have grown. Do not drink it.
Taste: An off or metallic taste is a clear indicator that the plastic bottle has degraded. A 'flat' taste is common for older water but does not indicate it is unsafe.

Conclusion

In summary, while the water itself has an indefinite shelf life, how long you can safely keep bottled still water depends entirely on its container and storage conditions. The 'best by' date is a guideline for peak freshness, not a hard-and-fast expiration date for safety. Storing unopened bottles in a cool, dark place away from chemicals will ensure they remain safe and pleasant to drink for years. Once opened, however, the water should be consumed within a few days. By understanding the science behind water storage and practicing proper handling, you can keep your emergency water supply safe and your everyday hydration fresh.

Additional resources

For more in-depth information on water safety and emergency preparedness, consult resources from organizations such as the U.S. Centers for Disease Control and Prevention (CDC). Proper water handling is an important aspect of overall health, and staying informed can help you make the best choices for your family's safety.

Final thoughts on plastic

It's important to remember that the degradation of plastic bottles not only affects the water's taste but also contributes to microplastic pollution. Reusing single-use plastic bottles is also not recommended due to potential bacterial buildup. Investing in reusable stainless steel or glass bottles for daily use is a more sustainable and safer option.

[IBWA link]: IBWA - Bottled Water Storage [CDC link]: CDC - Create an Emergency Water Supply

Frequently Asked Questions

Yes, in most cases, it is safe to drink bottled water after the 'best by' date, provided it has been stored correctly. The date refers to the plastic packaging, not the water itself, and indicates when the water is at its peak quality.

The date is primarily for the plastic bottle, which can degrade over time, especially when exposed to heat or light. As the plastic breaks down, it can leach chemicals into the water, affecting its taste and quality.

Drinking old bottled water that has been stored improperly might result in a less pleasant taste, but it is unlikely to cause serious harm if the seal was intact. However, it's best to check for any off-odors or cloudiness before consuming.

For maximum longevity and freshness, store bottled water in a cool, dark, and dry place, away from direct sunlight and strong-smelling chemicals.

It is generally not recommended to reuse disposable plastic water bottles. The plastic can degrade, and the porous material can harbor bacteria, especially after multiple uses and washings.

Freezing bottled water is not recommended. While it won't produce harmful carcinogens as some myths suggest, the repeated freezing and thawing process can cause the plastic to break down, potentially altering the water's taste.

Once opened, bottled water should be consumed relatively quickly to avoid contamination from bacteria. While not an exact science, most recommendations suggest consuming it within a few days, and faster if it's not refrigerated.