What Does the Expiration Date on Bottled Water Actually Mean?
An expiration date printed on a bottle of water is a regulation primarily concerning the packaging, not the liquid itself. Water is a stable inorganic compound (H2O) that does not inherently 'go bad' in the same way that perishable foods or drinks do. However, the container in which it is stored can and does degrade over time. The vast majority of bottled water is sold in plastic, typically polyethylene terephthalate (PET), which can break down over time and release chemicals.
For many years, some states, like New Jersey, required expiration dates on all food and beverage products, including bottled water, which led to the industry standard of a two-year 'best by' date. Although these laws have changed, the practice remains. This date is primarily for inventory management and consumer confidence, not a hard safety deadline for the water. The real risks associated with drinking out-of-date water stem from the plastic bottle and how it has been stored, not the water itself.
The Risks of Drinking Old Bottled Water
Several factors can compromise the quality and safety of bottled water over time, particularly when it's left past its suggested date. These include:
- Chemical Leaching: Plastic containers, especially when exposed to heat or sunlight, can leach chemicals like antimony and bisphenol A (BPA) into the water. While the FDA has not deemed current levels to be a significant risk for immediate harm, the long-term effects of cumulative exposure to these chemicals are still being studied. Reusing single-use plastic bottles exacerbates this risk.
- Bacterial Contamination: If a bottle has been opened, bacteria from the drinker's mouth can be introduced and multiply over time. Warm temperatures speed up this growth. Biofilms can form on the inside surfaces of the bottle, potentially leading to digestive issues. The risk of contamination is especially high with old, refilled plastic bottles.
- Absorption of Odors: Plastic is slightly porous and can absorb ambient gases and odors from the surrounding environment. This is why improperly stored bottled water can sometimes develop a strange or plastic-like taste. Storing water near cleaning chemicals or gasoline, for example, can affect its flavor.
Is it always unsafe to drink expired bottled water?
Not necessarily. If the water has been stored correctly—in a cool, dark place and has never been opened—it is likely safe to consume well past the date printed on the bottle. However, the taste may be affected due to the slight absorption of carbon dioxide from the air, making it taste a little 'stale'. The decision to drink it ultimately comes down to an assessment of its storage history and any visible or sensory signs of contamination.
Proper Storage vs. Poor Storage: A Comparison
To highlight the importance of proper storage, here's a comparison of how different conditions affect bottled water safety:
| Feature | Optimal Storage (e.g., Cool, Dark Pantry) | Poor Storage (e.g., Hot Car, Direct Sun) |
|---|---|---|
| Plastic Degradation | Minimal to no plastic breakdown; chemicals remain stable within the bottle. | Accelerated breakdown of PET plastic, increasing the risk of chemical leaching (e.g., antimony, BPA). |
| Chemical Leaching | Very low risk of chemicals leaching into the water, even years past the 'best by' date. | High risk of chemicals leaching into the water, potentially affecting taste and long-term health. |
| Bacterial Growth | Negligible growth in sealed bottles. Opened bottles are still at risk but slow down in cool temps. | Rapid bacterial multiplication, especially in opened bottles, creating a potential health risk. |
| Taste and Odor | Water retains its fresh, clean taste. No absorption of ambient odors from proper storage area. | Water may develop a distinct 'plastic' taste or absorb odors from volatile chemicals in the air. |
| Overall Safety | Generally safe to consume, especially if sealed. Follow sensory checks if past date. | Potentially unsafe. High risk of chemical and bacterial contamination. |
Tips for Ensuring Your Water is Safe to Drink
- Check the container: Before drinking, inspect the bottle for cracks, leaks, or any signs of degradation. If the bottle is worn, brittle, or discolored, discard it.
- Trust your senses: The first line of defense is your nose and eyes. If the water smells musty, chemical, or otherwise odd, or if it looks cloudy or discolored, pour it out.
- Store Properly: Always store bottled water in a cool, dark place away from direct sunlight, heat, and any volatile chemicals like household cleaners or gasoline.
- Use glass or steel: For long-term emergency water storage, or for reusable bottles, glass or stainless steel are safer options as they do not leach chemicals.
- Wash reusable bottles daily: For reusable bottles, wash thoroughly with hot soapy water after each use to prevent bacterial buildup.
- Rotate stock: For emergency supplies, rotate your water stock annually to ensure freshness and reduce the risk of plastic degradation over time.
Conclusion: The Container, Not the Content, is the Concern
Ultimately, the safety of drinking out of date water hinges on the container and its storage history. While the water itself is stable, the plastic bottle can and does degrade, posing potential health risks from chemical leaching and bacterial growth, particularly when exposed to heat and sunlight. Adopting proper storage habits and using glass or stainless steel for long-term storage are the safest approaches. When in doubt about an old bottle, it is always best to prioritize safety and simply pour it out. The expiration date is a good guideline, but a critical assessment of the bottle's condition and history is a more reliable indicator of its true drinkability.
