What happens if I drink expired mineral water? Unpacking the Safety Risks

November 25, 2025 •

4 min read

According to the U.S. Food and Drug Administration (FDA), properly sealed and stored bottled water has an indefinite shelf life, but consumer confusion persists because of printed expiration dates. This raises the question: what happens if I drink expired mineral water and are there any real dangers?

Quick Summary

The expiration date on bottled water relates to the packaging, not the water itself. While consuming properly stored, old bottled water is generally safe, poor storage can cause plastic chemicals to leach into the water, affecting its taste and potentially introducing harmful compounds like microplastics.

Key Points

The bottle, not the water: The expiration date primarily concerns the plastic container, which can degrade over time, not the water inside.
Heat accelerates leaching: Storing water bottles in hot places, like a car or sun-exposed garage, speeds up the release of chemicals from the plastic into the water.
Check for visual cues: Signs of compromised water include cloudiness, discoloration, strange smells, or an unusual taste.
Microplastics are a concern: Plastic degradation can introduce microplastics, with potential long-term health effects that are still under investigation.
Proper storage is key: Keep bottled water in a cool, dark place away from chemicals to preserve its quality and prevent leaching.
Taste changes can happen: Even with proper storage, older water may develop a stale or slightly different taste due to interaction with the plastic.

Is it the Water or the Bottle that Expires?

Contrary to popular belief, the expiration date found on bottled water is not for the water itself, but for the plastic bottle that contains it. Pure water (H₂O) does not expire in the traditional sense because it lacks the organic matter that supports microbial growth, like the content found in milk or juice. The expiration date, or more accurately, the "best by" date, is a regulatory requirement for a consumable product and acts as a manufacturer's guideline for peak taste and quality. After this date, the company no longer guarantees the optimal freshness of the product, primarily because of the container's potential degradation over time.

The Problem with Plastic Degradation

Plastic bottles, typically made from polyethylene terephthalate (PET), are not entirely inert. They are slightly permeable and can break down over an extended period, particularly when exposed to certain environmental factors. This degradation process causes trace amounts of chemicals from the plastic to leach into the water. Some of these compounds include antimony, a metalloid used in PET manufacturing, and microplastics—tiny plastic fragments that have become a growing environmental and health concern.

The Impact of Improper Storage

Storage conditions are the most critical factor in determining the actual safety and quality of expired bottled water. Heat and sunlight are the primary catalysts for plastic degradation and chemical leaching. A sealed bottle left in a hot car, a sun-exposed garage, or near household chemicals can significantly accelerate the release of these compounds. This process can not only compromise the safety of the water but also negatively affect its taste and smell, making it unpleasant to drink.

Recognizing the Signs of Compromised Water

Before consuming old bottled water, it's essential to assess its condition. While many bottles past their "best by" date are perfectly safe, some signs indicate that the quality has been compromised and it should be discarded.

Cloudiness or Discoloration: The water should be perfectly clear. Any cloudiness, froth, or a greenish/blue tint could indicate contamination from dirt, algae, or germs.
Strange Smell: Give the water a sniff. If it has a musty, moldy, chemical, or metallic odor, it's best to throw it out.
Unusual Taste: Even if it looks and smells normal, a sip might reveal an off-putting taste, such as a plastic-like or bitter flavor.
Damaged Bottle: If the bottle itself is warped, soft, bloated, or has a compromised seal, there's a higher risk of external contaminants entering the water.

Potential Health Implications

For most people, drinking expired bottled water that has been stored properly will not cause an immediate illness. The primary concern lies in long-term consumption and the cumulative effects of ingesting low levels of plastic-derived chemicals and microplastics. Research has linked higher microplastic intake to various health issues, though the full scope of risks is still being studied. Studies suggest microplastics can potentially cross biological barriers in the body and interfere with cellular processes.


Feature	Properly Stored Expired Water	Improperly Stored Expired Water
Safety	Generally safe, but with potential for minor taste changes.	Higher risk of chemical leaching and potential microbial contamination.
Taste	Might be stale or slightly "flat."	Often has an unpleasant, plasticky, metallic, or chemical flavor.
Appearance	Clear and free of particles.	Can appear cloudy, discolored, or have floating particles.
Bottle Integrity	Bottle remains firm and seal is intact.	Bottle may be warped, soft, or damaged by heat/sunlight.
Best Action	Safe to drink, but best for emergency use or non-consumption purposes.	Discard immediately to avoid health risks.

Proper Storage is Your Best Defense

To ensure the best quality and safety of your bottled water, proper storage is key. The International Bottled Water Association recommends storing sealed bottles in a cool, dark, and dry place. A pantry, basement, or cupboard is an ideal location. Avoid leaving water bottles in a car, a hot garage, or any area exposed to direct sunlight or temperature extremes. Furthermore, keep bottled water away from strong-smelling household chemicals, as the porous plastic can allow odors to permeate the container and affect the water's taste. For emergency supplies, the Red Cross recommends replacing commercial bottled water annually to maintain freshness.

Conclusion: Making an Informed Choice

Ultimately, whether you choose to drink expired mineral water depends on how it was stored and your personal comfort level with potential taste changes and chemical exposure. While the water itself does not spoil, the degrading plastic container and poor storage conditions present the real risks. By being aware of these factors, inspecting the bottle before consuming, and prioritizing proper storage, you can make an informed decision about the quality and safety of your drinking water. For long-term peace of mind and the purest water, many opt for filtered tap water or invest in stainless steel bottles for storage and reuse.

For more detailed storage recommendations, the International Bottled Water Association offers useful resources.

Frequently Asked Questions

If the water has been properly stored and the bottle is sealed, it is unlikely to cause immediate illness. The main risks are potential taste changes and long-term chemical exposure, not instant sickness, unless the water has been contaminated post-opening.

Chemicals like antimony, used in PET plastic manufacturing, and microplastics can leach into bottled water. This process is accelerated by improper storage, especially exposure to heat and sunlight.

If kept sealed and stored in a cool, dark place, bottled water can be safe to drink indefinitely according to the FDA. However, manufacturers often recommend consuming it within two years for optimal taste and quality, and it's best to rotate stock.

Yes. While plastic bottles can degrade over time, glass bottles are non-porous and do not leach chemicals, meaning water stored in glass has a much longer shelf life with no change in taste or quality.

Expiration or 'best by' dates on bottled water are often for regulatory and inventory management purposes. They represent the period for which the manufacturer guarantees the product's peak quality and taste, which can be affected by the packaging over time.

If stored properly in a cool, dark place, you can likely still drink it. However, if the water has an odd smell, taste, or appearance, discard it. For emergency preparedness, rotating your stock every year is a good practice.

Recent studies have detected microplastics in bottled water and linked them to potential health issues such as chronic inflammation, hormone disruption, and cancer, though the long-term effects are not fully understood.