How Long Can You Store Water?
Water is one of the simplest things to store for emergencies—and one of the easiest to misunderstand. You may have heard everything from “water never expires” to “you have to rotate every few months.” The truth is somewhere in between and depends on how the water is stored, where it’s stored, and what it’s stored in.
This guide breaks down how long you can store water in different situations, including tap water, bottled water, and water explicitly treated for long-term storage in emergency water tanks.
Why Stored Water Has a Shelf Life
What Causes Water to Go “Bad”?
Pure H2O doesn’t really “go bad” on its own. What changes over time are:
- Contaminants introduced during filling (from hoses, dirty containers, or unclean faucets)
- Microorganisms (bacteria, algae, etc.) that can grow if they’re present and the conditions are right
- Chemical leaching from low-quality plastics or non-food-grade containers
- Taste and odor changes as chlorine dissipates and the water absorbs smells from its environment
So when we talk about “how long water lasts,” we’re really talking about how long it stays safe, clean, and pleasant to drink in a particular container and location.
Contamination Risks in Home Storage
Most problems with stored water come from the storage setup, not the water itself. Common issues include:
- Using non-food-grade containers (old paint buckets, used juice jugs, etc.)
- Filling with an unapproved or leaded garden hose instead of a potable water hose
- Storing tanks in direct sunlight, which heats water and encourages algae growth
- Leaving containers partially open or unsealed, allowing dust and bugs to get in
Good containers and good habits massively extend the usable life of stored water. Check out these options:
How Long Can You Store Tap Water?
Tap water storage time depends on whether you treat it and how you store it.
Stored in Food-Grade Containers (Properly Sanitized)
If you sanitize your containers, use municipal tap water, and seal the container, general preparedness guidelines suggest:
- Untreated tap water in clean, food-grade containers: plan to rotate every 6–12 months.
- Cool, dark storage (50–70°F): closer to the 12-month end of that range.
- Hot garage or direct sun: stay closer to the 6-month mark and consider treating the water.
- A water treatment solution can extend the life of your water up to 5 years!
Even after a year, water that was stored correctly often remains safe if the container is intact and the water looks, smells, and tastes normal. But for emergency planning, it’s smart to schedule regular rotation so you’re not guessing during a crisis.
Stored Without Proper Sanitation
If you:
- Skimped on sanitizing the container first, or
- Used a non-potable hose, or
- Can’t remember how clean things were when you filled them
…treat that water with more caution. In those cases:
- Try to use and replace within 3–6 months.
- If it’s older, plan to disinfect before drinking (boil, use water treatment drops, or a trusted filter that removes bacteria/viruses).
In an emergency, questionable water can still be life-saving—but you’ll want a way to make it safe.
How Long Can You Store Bottled Water?
Bottled water has its own rules because it’s professionally filtered, sealed, and labeled—but it’s still affected by heat, light, and plastics.
Unopened Commercial Bottled Water
Most bottled water companies (like Dasani) print a “best by” date, often 1–2 years from bottling. That date is usually about taste and packaging, not sudden spoilage.
- Stored cool and dark: Unopened bottled water can remain safe for years past the printed date, though flavor may slowly change.
- Exposed to heat (hot garage, car, etc.): Avoid storing long-term. High heat can break down plastics and affect both safety and taste.
For emergency storage, consider unopened bottled water to have a practical shelf life of 1–3 years. It may last longer, but it’s wise to rotate regularly:
- Write the purchase date on the case.