The human body is about 70 percent water, and that level has to stay within a narrow range for everything else to work. You lose water constantly through sweat, saliva, tears, and urination, and you have to replace it. A person needs roughly 2 to 4 liters (half a gallon to a gallon) a day, and more in intense heat or hard physical work. In an emergency, getting that much every day may not be possible, and most of us don’t live near a potable spring. So the practical answer is to store water before you need it.
Storage is more than filling jugs. The container you choose affects how long the water stays safe, how easily you can move it, and how much you can keep. This guide covers how long water keeps, how to prepare containers, and the strengths and drawbacks of each type, from soda bottles to 55-gallon drums.
Does stored water expire? #
Yes, in a sense. Water has no sugar or protein for microbes to feed on, so it doesn’t rot the way food does. But it changes. Water exposed to air absorbs carbon dioxide, and a small fraction converts to carbonic acid, which can form bicarbonate and carbonate. That lowers the pH, leaving the water slightly acidic and altering the taste. In a sealed plastic container, heat can build up and react with the plastic, and some plastics can release bisphenol-A (BPA), a hormone disruptor. Water in that state is not worth drinking.
Properly stored municipal water should keep indefinitely in principle, but plan to replace it every 6 to 12 months for the best taste. Swapping containers about every six months is a sound rule. Water from a private well, spring, or other untested source should be purified before you store it.
Bottled water is a special case. The U.S. FDA does not set a shelf life for it, but a sensible limit is no more than two years for non-carbonated water and one year for sparkling.
Where you keep it matters as much as what it is in. Store water in a cool, dark place, away from sunlight, ideally between 50 and 70 degrees Fahrenheit. Sun and heat slowly degrade plastic and give water an off smell and flavor.
Preparing any container #
Before you fill a container, clean it.
- Wash it thoroughly.
- Sanitize it with dilute household bleach: one teaspoon of liquid bleach per gallon of water. Use unscented bleach, so you don’t transfer a scent to the water.
- Rinse it with potable water.
- Fill it and cap it tightly.
- Label it with the date, so you know when to rotate it.
Between uses, wash, sanitize, and disinfect again. You can also disinfect water itself by boiling it at a rolling boil for a minute, then sealing the container tightly.
Plastic containers #
Plastic is the common choice because it is cheap, light, and available.
Reused beverage bottles. The cheapest approach is to reuse food-grade plastic soda bottles or milk jugs. Two-liter bottles work well. Clean and sanitize them as above.
HDPE (high-density polyethylene). A durable, food-safe plastic resistant to impact and chemicals. HDPE containers are lightweight and easy to handle.
PETE (polyethylene terephthalate). Light and transparent, common in beverage bottles, durable, and recyclable.
Dedicated plastic storage. Purpose-made containers range from about 5 to 55 gallons. Choose food-grade, BPA-free plastic, and remember that stored water is heavy and exerts a lot of pressure, so the container must be structurally strong, sturdy, and durable. Look for one light enough to carry when empty.
The downsides: plastic can degrade over time, and UV damages it. Keep plastic containers in a cool, dark place, and inspect them regularly. Replace any that show wear.
Glass bottles and jars #
Glass doesn’t leach chemicals and doesn’t absorb odors, so water tastes the way it should. Many sources rank it highest for purity of taste.
Clear glass lets you check the water without opening it, but sunlight passes through and can encourage algae or bacterial growth. Dark glass, such as amber or cobalt blue, blocks UV rays and is better for long-term storage.
The trade-offs are weight and fragility. Glass can break, which is a real problem in an emergency when you can’t afford to lose the reserve. Store it securely. It suits a home pantry better than a bug-out bag.
Stainless steel #
Stainless steel is sturdy, rust-proof, and safe, which is why it is widely considered the best material for water storage. It resists corrosion, cleans easily, is portable, and is recyclable. It also insulates well and keeps water cool.
Not every stainless steel is suitable. Most types are made for industrial use, and the grade recommended for food and water is 316. Check what you’re buying. Food-grade steel is also essential, and stainless containers aren’t ideal for acidic liquids, which can corrode the metal over time. Steel costs more than plastic, but its longevity usually justifies it.
Aluminum, ceramic, and enamel #
Aluminum bottles are light, tough, and recyclable, and they conduct heat well. Raw aluminum reacts with water, which can leave a metallic taste or leach unwanted substances. Water containers are therefore lined with a food-grade coating. Buy only those labeled as safe for water storage, and avoid acidic or carbonated liquids, which can corrode the metal or damage the lining.
Ceramic is non-reactive and non-porous, so it won’t absorb odors or flavors, and it insulates well. It is also fragile and heavy, which makes it better for stationary storage than for emergency transport.
Enamel-coated containers combine metal strength with a non-reactive surface. Low-quality enamel can contain lead or other toxic materials, so buy food-grade containers labeled safe for water. Chipped or scratched enamel exposes the metal underneath, so inspect and replace damaged pieces.
Flexible, collapsible, and bathtub storage #
When space or weight matters, flexible options help.
Flexible pouches and collapsible containers are light, roll up when empty, and resist punctures. They suit camping, hiking, and cramped quarters. They are less durable than rigid containers, can degrade under prolonged sun or extreme temperatures, and don’t insulate. Keep them away from sharp objects and inspect them often.
The WaterBOB is a large, sturdy plastic bag that you place in your bathtub when you see trouble coming. You fill it from the tap, close it with its airtight access point, and draw from it as needed. The access point reseals, and the bag holds up to 100 gallons. It makes sense if you get advance warning of a storm or outage.
Barrels and large-capacity storage #
Barrels and drums are for volume. They are typically HDPE, with airtight seals and spigots for easy access, and many stack to save space. They offer much larger capacity than bottles, which suits a household stockpile.
They are heavy and bulky when full, so place them on a stable, secure base before filling. Clean them regularly, and rotate the water every six months to avoid stagnation and bacterial growth.
Preserving stored water #
To keep water fresh and tasting good for long periods, you can add a preservative. Chlorine is the standard choice because it kills most microbes. Granular calcium hypochlorite is generally better than household liquid bleach for this purpose, because ordinary bleach degrades over time and may not disinfect your water when you need it.
If your container is plastic, keep it out of direct sunlight. Many plastic containers are tinted to block light, but heat can still build up inside.
Distillation is another purification method, though not one for routine storage. It boils water and collects only the condensing vapor, and in doing so removes microbes, heavy metals, salts, and most other chemicals.
How to choose #
Weigh these factors before buying:
- Capacity. Decide how much you need, remembering the 2 to 4 liters per person per day figure, and make sure you have space for it. Larger containers may need extra support.
- BPA-free materials. BPA can leach from some plastics and cause health risks.
- Durability. The container has to survive handling and the environment it sits in.
- Airtight seals. A secure seal prevents contamination and evaporation.
- UV protection. If any sunlight reaches the container, choose one that resists it.
- Water treatment. Treat or disinfect before storage, either with commercial treatment solutions or by boiling.
A practical setup #
You don’t need to pick a single container. A mixed approach covers more scenarios. Keep a supply of reused two-liter bottles and milk jugs for cheap, flexible storage. Add a few dedicated 5- to 55-gallon containers, in food-grade plastic or 316 stainless steel, for bulk. Keep a WaterBOB with your emergency supplies for warning-time storage. Add collapsible containers for the vehicle or bug-out bag.
Label everything with the fill date, keep it in a cool, dark place, and replace the water on a schedule. Stored water can go bad, but with the right container and a little maintenance, it will be there when you need it.