Strictly speaking, water cannot go off in the same way food does. Pure water does not contain the organic matter necessary for microbial spoilage.
Why Pure Water Doesn't "Go Off"
The fundamental reason water does not "go off" in the traditional sense is its chemical composition. Unlike perishable foods, water lacks key components that microbes feed on. As the reference states, water cannot go off because it does not contain proteins or sugars. These are the primary nutrients that microorganisms, such as bacteria and fungi, break down, leading to spoilage, fermentation, and the unpleasant smells or textures associated with food going bad.
Since water itself lacks these breakdown components, it doesn't support the kind of microbial growth that leads to spoilage.
What Can Happen to Bottled Water Over Time?
While water doesn't spoil, its quality can change, and it can become less desirable or even unsafe to drink due to external factors.
1. Taste Alterations
- Carbon Dioxide Absorption: If left exposed to the air, water will absorb carbon dioxide, which can slightly alter its pH and give it a subtly different, often "stale," taste.
- Plastic Leaching: Over time, chemicals from plastic bottles (like PET or BPA in some older plastics) can leach into the water, especially when exposed to heat or sunlight. This can impart a plastic-like taste and potentially raise health concerns.
- Odor Absorption: Water can absorb odors from its surrounding environment, such as chemicals, cleaning supplies, or even strong food smells, impacting its taste.
2. Contamination and Microbial Growth (External Factors)
- Introduced Microbes: While water itself doesn't "go off," the container or the act of drinking can introduce microbes. If you drink directly from a bottle, bacteria from your mouth can enter the water. Given enough time, warmth, and potentially trace organic matter (like saliva), these bacteria can multiply, making the water unappetizing or potentially unsafe.
- Algae Growth: If bottled water, particularly tap water or spring water with trace minerals, is exposed to sunlight, algae can begin to grow. This is visible as a green film and while often harmless in small amounts, it makes the water unappealing.
- Dust and Debris: An open bottle can accumulate dust, dirt, or other airborne particles, compromising the water's purity.
3. "Best By" Dates on Bottled Water
Most bottled water comes with a "best by" or expiration date. This date typically refers to the packaging rather than the water itself. Over extended periods, the plastic bottle can degrade, potentially leading to:
- Leaching of chemicals into the water.
- Compromised seal integrity, allowing contaminants or odors to enter.
- Loss of taste quality due to external absorption or plastic interaction.
Key Differences: Water vs. Spoilable Foods
To understand why water is unique, consider how it differs from foods that readily spoil:
| Feature | Pure Water | Spoilable Foods (e.g., Milk, Meat) |
|---|---|---|
| Organic Matter (Nutrients) | None or negligible | High (proteins, fats, carbohydrates, sugars) |
| Microbial Activity | Minimal to none (in pure water) | High (bacteria, molds, yeasts thrive) |
| Spoilage Mechanism | External contamination, taste alteration | Microbial decomposition of organic matter |
| Spoilage Indicators | Stale taste, plastic taste, visible algae | Foul odor, slime, mold, discoloration, gas |
| Primary Risk | Contamination, unpleasant taste | Food poisoning, significant health risks |
Tips for Storing Bottled Water
To maintain the best quality of your bottled water and ensure it remains safe to drink:
- Store in a Cool, Dark Place: This minimizes plastic degradation and chemical leaching, and prevents algae growth.
- Keep Sealed: Ensure bottles are tightly capped to prevent absorption of odors or entry of contaminants.
- Avoid Direct Sunlight: Sunlight accelerates plastic breakdown and promotes algae growth.
- Clean Reusable Bottles Regularly: If using reusable bottles, wash them thoroughly with soap and hot water, or in a dishwasher, after each use to prevent bacterial buildup.
- Don't Reuse Single-Use Plastic Bottles Indefinitely: While convenient, these plastics can degrade over time and harbor bacteria if not cleaned properly.
In conclusion, while water itself doesn't "go off" due to its lack of proteins and sugars, it can become unpleasant or unsafe to drink if contaminated or improperly stored.
