Is It Safe to Drink Expired Water? The Surprising Truth About Bottle Expiration

December 23, 2025 •

4 min read

While pure water itself does not go bad, the expiration date on a water bottle is for the plastic container, not the liquid inside. This crucial distinction raises the important question: is it safe to drink expired water?

Quick Summary

The expiration date on bottled water refers to the plastic packaging, which can degrade and leach chemicals over time. Improper storage and handling increase contamination risks, potentially affecting taste and safety.

Key Points

Expiration Dates are for the Bottle: The date on a water bottle refers to the plastic container, not the water itself, which is chemically stable and does not spoil.
Heat Causes Leaching: Exposure to heat and sunlight can cause chemicals like BPA and antimony to leach from plastic into the water, potentially affecting taste and health.
Storage Conditions are Critical: Always store bottled water in a cool, dark, and dry place, away from direct sunlight, solvents, and chemicals to prevent contamination.
Inspect for Signs of Spoilage: Before consuming, check for off-odors, unusual tastes, cloudiness, or visible particles, and discard if any are present.
Glass and Steel are Safer for Long-Term Storage: For emergency preparedness, glass or stainless steel containers are superior to plastic for long-term water storage to avoid chemical leaching.
Opened Bottles are High-Risk: Once opened, a water bottle can harbor bacteria, and should be consumed within a few days, especially if not refrigerated.
Trust Your Senses: When faced with an old bottle of water, rely on your sight, smell, and taste to determine if it is safe, and err on the side of caution.

What the Expiration Date on Bottled Water Really Means

Unlike milk or juice, water does not inherently spoil. It is a stable compound composed of two hydrogen atoms and one oxygen atom. The 'best by' or 'use by' date stamped on bottled water is not a safety warning about the water, but rather a guideline for the integrity of its plastic container. This industry standard arose partly from a defunct New Jersey law in 1987 that mandated expiration dates on all food products. While the law has been repealed, the practice has persisted, primarily for stock rotation purposes and to ensure optimal taste. The U.S. Food and Drug Administration (FDA) has stated that properly sealed and stored bottled water has an unlimited shelf life.

The Dangers of Degrading Plastic

If the water itself is fine, why is there a concern? The primary reason is the plastic bottle. Most single-use bottles are made from polyethylene terephthalate (PET) plastic. Over time, particularly when exposed to heat and direct sunlight, this plastic can degrade and release small amounts of chemicals, such as antimony and bisphenol A (BPA), into the water. While typically below FDA limits, excessive heat can accelerate this process, potentially affecting the water's taste and raising long-term health concerns related to endocrine disruption and other issues.

Contamination Risks from Improper Storage

Plastic is also slightly permeable, meaning that if bottles are stored near strong-smelling chemicals, like household cleaners or gasoline, the water can absorb the vapors and take on an unpleasant taste or odor. Furthermore, once a bottle is opened, it is exposed to airborne contaminants and microorganisms from your mouth, which can multiply over time, especially at warmer temperatures. Reusing single-use plastic bottles exacerbates this risk.

How to Assess Your Expired Water

Before drinking water past its 'best by' date, a quick sensory check is a smart precaution. If you notice any of these signs, it is best to discard the water:

Off-odor: A musty, moldy, or chemical-like smell could indicate contamination or plastic degradation.
Unusual taste: Water that tastes stale, metallic, or noticeably plastic is a clear sign that its quality has been compromised.
Cloudiness or discoloration: Any change in the water's appearance, such as a green, brown, or cloudy tint, could signal bacterial growth or other contamination.
Visible particles: Floating sediment or particles suggest the bottle's material is breaking down.

Proper Water Storage for Longevity

To maintain the highest quality and safety for bottled water, whether for daily use or emergency preparedness, proper storage is critical.

Store bottles in a cool, dark, and dry place, such as a pantry or basement.
Keep them away from direct sunlight, which accelerates plastic degradation.
Avoid storing near household chemicals, solvents, or gasoline due to permeability.
For long-term storage, consider rotating your stock annually.
Store opened bottles in the refrigerator and consume them within a few days.

Comparison of Storage Container Materials

When considering long-term water storage, the container material is a key factor. The following table compares common options:


Feature	PET Plastic Bottles	Glass Bottles	Stainless Steel Bottles
Cost	Low	High	High
Durability	Low (prone to cracks)	Medium (breakable)	High (impact resistant)
Chemical Leaching Risk	High (especially with heat)	None	None
Taste/Odor Absorption	High (permeable)	None	None
Shelf Life	Best consumed within 2 years	Indefinite	Indefinite
Weight	Lightweight	Heavy	Medium-Heavy

The Verdict: Is It Worth the Risk?

Technically, an unopened, properly stored bottle of water past its expiration date is likely safe to drink. The issue, however, lies in the many unknowns surrounding its journey from the factory to your lips. You can't be certain of the storage conditions it faced in transit or on a store shelf. With the potential for chemical leaching from the plastic and the risk of contamination in opened bottles, it's a gamble. For the safest and best-tasting experience, sticking to water well within its recommended 'best by' date and practicing proper storage is the best approach. When in doubt, don't risk it, and discard any water that shows signs of spoilage. For more information on water quality and safety, refer to reputable sources like the International Bottled Water Association.

Conclusion: Prioritize Freshness and Proper Storage

While water itself does not expire, the bottle it comes in can degrade, leading to potential chemical leaching and taste changes. Improper storage, especially exposure to heat and sunlight, significantly increases these risks. To ensure safety and optimal quality, pay attention to the 'best by' date as a guide, inspect water for signs of spoilage, and practice proper storage techniques in a cool, dark place. By being mindful of these factors, you can make an informed decision about drinking older bottled water and prioritize your hydration healthily.

Frequently Asked Questions

While it's unlikely, you could get sick if the water has become contaminated due to a compromised seal or improper storage, which could lead to bacterial growth. The main risks, however, are chemical leaching from degrading plastic and poor taste, not the water itself spoiling.

The expiration date is primarily a 'best by' indicator for the plastic bottle, not the water inside. It helps manufacturers and retailers with stock rotation and ensures optimal taste quality for consumers.

Yes, older bottled water can develop a stale or off-putting taste. This is often caused by the plastic degrading or the water absorbing trace amounts of chemicals or odors from the bottle and its surroundings.

Drinking water from a bottle left in a hot car is not recommended. Excessive heat accelerates the breakdown of the plastic, increasing the likelihood of chemicals leaching into the water and affecting its taste.

It is generally not recommended to reuse single-use plastic bottles. The plastic can degrade with repeated use and washing, and the bottle can harbor bacteria from your mouth and hands.

For long-term storage, keep water in food-grade glass or thick, BPA-free plastic containers in a cool, dark place away from chemicals. Rotate your supply every 6-12 months for optimal freshness.

Boiling water will kill any potential microbial contaminants that might be present but will not remove any chemicals that have already leached from a degrading plastic bottle. If the water tastes or smells off, it's best to discard it.