The ability to store potable water for an extended period is a cornerstone of emergency preparedness. The shelf life of your stored water is not a fixed number but rather a variable determined by several key factors. These include whether the water is commercially bottled or tap-filled, the container material, and the storage environment.
Commercially Bottled Water
Commercially packaged bottled water often comes with a 'best before' or expiration date, but this date refers to the packaging, not the water itself. The plastic (Polyethylene Terephthalate or PET) used for most bottles can degrade over time, leaching chemicals into the water and affecting its taste. For this reason, manufacturers place a date on the product to guarantee quality and taste. If stored correctly in a cool, dark place, unopened bottled water can remain safe for many years, but the taste may become stale.
Best practices for commercially bottled water storage:
- Store in a cool, dark location away from direct sunlight, which accelerates plastic degradation.
- Keep away from strong-smelling chemicals like gasoline, cleaning supplies, and pesticides, as plastic is permeable and can absorb odors.
- Rotate your stock periodically to ensure you are consuming the freshest water possible.
Storing Tap Water
When storing your own tap water, proper preparation and rotation are essential for safety. Tap water is already treated with chlorine, which helps to kill bacteria, but this disinfectant dissipates over time.
Step-by-step guide for tap water storage:
- Select food-grade containers: Use clean, food-grade containers made from materials like HDPE plastic, glass, or stainless steel. Avoid using containers that have previously stored milk or chemicals.
- Clean and sanitize: Wash containers thoroughly with soap and water, then sanitize with a diluted, unscented chlorine bleach solution (1 teaspoon of bleach per quart of water). Shake, let sit for 30 seconds, and rinse.
- Fill and treat: Fill the container with fresh tap water. For an extra safety margin or for well water, add a small amount of unscented chlorine bleach (e.g., 8 drops per gallon). Cap tightly without touching the inside of the lid.
- Label and store: Label containers with the fill date. Store them in a cool (50–70°F), dark, and dry place, away from chemicals and out of direct sunlight.
- Rotate: The CDC recommends replacing home-stored tap water every six months to maintain quality.
Storing Filtered Water
Filtered water, such as from a pitcher or faucet filter, removes chlorine and other disinfectants, making it more susceptible to bacterial growth. It has a much shorter shelf life than tap water.
Recommended storage for filtered water:
- Refrigerator storage: Filtered water can be safely stored in the refrigerator for 3–5 days in a sealed, clean container before it should be replaced.
- Avoid room temperature: Do not leave filtered water out at room temperature for extended periods, as it is a breeding ground for bacteria.
Long-Term Storage Containers Comparison
Proper container selection is critical for long-term water storage. The material affects both the water's taste and its safety over time.
| Container Type | Pros | Cons | Recommended Shelf Life (Home-Filled) |
|---|---|---|---|
| Food-Grade Plastic (HDPE) | Durable, lightweight, available in large sizes (55-gallon barrels). BPA-free options exist. | Some plastics are permeable to chemical vapors and can affect taste over time. | Rotate every 6–12 months. |
| Glass | Impermeable to gases, does not leach chemicals, does not affect taste. | Breakable, heavy, not ideal for emergency mobility. | Indefinite, but check for any signs of contamination. |
| Stainless Steel | Durable, non-porous, resistant to corrosion (chromium alloy). | Can be expensive and heavy. Cannot be treated with chlorine, which can degrade the protective layer. | Indefinite, with proper handling. |
| Repurposed Plastic | Inexpensive, readily available. | Not food-grade, hard to clean thoroughly, can degrade quickly. | Not recommended for long-term storage, high contamination risk. |
How to Tell if Stored Water is Unsafe
Even with proper storage, it's important to inspect your water before consumption, especially if it's been stored for a long time. Water that has gone bad is contaminated by bacteria or leached chemicals, making it unsafe to drink.
Signs of contamination to look for include:
- Cloudiness or visible particles: This suggests microbial growth or a breakdown of the container material.
- Off-putting odor: A foul, stale, or chemical smell can indicate contamination.
- Strange taste: An oily, metallic, or plastic-like taste suggests chemical leaching.
If you have any doubt about the safety of your stored water, it's best to discard it or purify it using a reliable method, such as boiling or chemical treatment, before consumption.
Conclusion
While the concept of storing drinkable water may seem simple, its longevity is a nuanced issue influenced by the source, container, and storage conditions. Commercial bottled water can last for years in its sealed plastic container, but tap water you store at home should be rotated every six to twelve months to ensure freshness and safety. By selecting the right food-grade containers, storing them correctly in a cool, dark place, and regularly refreshing your supply, you can maintain a safe and reliable water source for any emergency.
