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If you fill a clean, food-grade plastic container with safe drinking water, a practical rule is to replace the stored water every six months. That is the current CDC recommendation for water you store yourself. Keep the container tightly closed, cool, out of direct sunlight, and away from gasoline, pesticides, and other chemicals.
Six months is a rotation guideline, not a point when water suddenly becomes unsafe. How long water stays drinkable depends on the water you started with, the container, how well it was cleaned, storage temperature, and whether the container has been opened.
How Long Different Types of Stored Water Last
| Stored water | Practical guidance |
|---|---|
| Tap water placed in your own food-grade plastic container | Replace every 6 months |
| Unopened commercially bottled water | Follow the expiration or use-by information on the bottle |
| Water in a container that has been opened repeatedly | Contamination risk increases; use careful dispensing and do not count on the original storage period |
| Rainwater or other untreated water | Do not assume it is drinkable based on storage time alone |
The CDC considers unopened commercially bottled water the safest and most reliable choice for an emergency water supply and recommends following the expiration date on store-bought water.
Why Stored Water Has a Six-Month Rotation
Water does not spoil in the same way that milk or juice does. The bigger concern is contamination.
Germs may enter when you fill the container, touch its inside surfaces, open it, or dip a cup or other object into the water. A poor seal can also let dirt and insects enter.
A six-month rotation gives you a simple schedule for emptying the container, checking it, cleaning it, and starting again with fresh drinking water.
Do not assume that water becomes dangerous exactly six months after filling. Likewise, do not assume that water stored for less than six months must be safe. The way it was collected and handled matters just as much as its age.
Use a Food-Grade Plastic Container
For drinking water, use a container made for storing food or water.
The CDC recommends food-grade water storage containers when possible. A good container should also have:
- A lid or cap that closes tightly
- Durable construction
- A small or narrow opening that limits contact with the water
- A design that lets you pour or dispense water without putting your hands inside
A spigot can be useful on larger containers because it reduces the need to open the top every time you need water.
If you cannot tell whether a plastic container is food-grade, check the manufacturer's intended use rather than relying only on its color or recycling number.
Never Reuse a Chemical Container for Drinking Water
Do not store drinking water in a container that previously held pesticides, fuel, bleach, solvents, or other toxic chemicals.
Cleaning the container does not guarantee that chemical residues have been removed from the plastic. The CDC specifically advises against using containers that have held toxic chemicals.
Clean and Sanitize the Container Before Filling It
Starting with a clean container greatly lowers the chance of contaminating otherwise safe water.
The CDC gives the following method for preparing a water storage container:
- Wash the container with soap and water.
- Rinse it completely.
- Make a sanitizing solution using 1 teaspoon of unscented household chlorine bleach in 1 quart of water. The bleach should contain 5% to 9% sodium hypochlorite.
- Put the solution in the container and close it.
- Shake it so the solution contacts all inside surfaces.
- Let it sit for at least 30 seconds.
- Pour the solution out.
- Allow the container to air-dry.
- Fill it with clean drinking water and close it tightly.
This bleach mixture is for sanitizing the empty container. It is not the same as the amount used to disinfect questionable drinking water. Do not add bleach to stored water without following appropriate drinking-water disinfection instructions.
Where You Store the Container Matters
A clean container can still be a poor storage setup if it sits in the wrong place.
The CDC recommends keeping stored drinking water in a cool location, away from direct sunlight and toxic substances. Its emergency-storage guidance gives a preferred temperature range of about 50°F to 70°F.
A closet, cool storage room, or other protected indoor area is usually better than a hot garage or outdoor shed.
Heat and sunlight can also shorten the useful life of a plastic container. Check containers regularly for cracks, leaks, damaged caps, or other signs of deterioration.
Keep stored water away from:
- Gasoline
- Paint and solvents
- Pesticides
- Household chemicals
- Areas that become very hot
- Direct sunlight
Do not assume a closed plastic container protects water from every nearby chemical.
Opening the Container Changes the Situation
A sealed container is easier to protect from contamination than one you use every day.
Each time you open it, you create another chance for germs to enter. Contamination is especially easy if someone puts a hand, cup, scoop, hose, or dirty pump into the water.
The CDC recommends avoiding contact with the stored water or the inside of the container. If a scoop must be used, it should be clean each time.
Review practical steps for storing water for 6 months to evaluate the main trade-offs before the next design decision.
For frequently used water, a container with a protected spigot or small dispensing opening can reduce contact.
Can Water Be Drinkable After Six Months?
It may be, but you should not use age alone to make that decision.
Properly stored water does not automatically become contaminated on the first day after the six-month mark. However, the CDC's simple household recommendation is to rotate self-filled stored water every six months rather than trying to determine how much longer each batch might remain suitable.
For a household emergency supply, rotating the water is usually easier than trying to evaluate old stored water.
You can use the old water for suitable non-drinking purposes when appropriate, then clean the container and refill it with fresh drinking water.
When You Should Not Drink Stored Water
Do not drink stored water if you know or suspect that fuel or toxic chemicals have contaminated it. Boiling or ordinary disinfection cannot make chemically contaminated water safe.
Also avoid drinking the water if the container has:
- Been left open or unsealed
- Developed a crack or damaged lid
- Been flooded or exposed to dirty water
- Had unknown substances placed in it
- Previously contained toxic chemicals
An unusual color or odor is another reason not to use the water for drinking.
However, clear water with no smell is not proof that it is safe. Many harmful germs and chemicals cannot be detected by sight, smell, or taste.
What About Rainwater Stored in a Plastic Container?
The six-month storage rule does not turn untreated rainwater into drinking water.
Roof runoff can pick up bird droppings, animal waste, dust, roofing materials, chemicals, and other contaminants before it reaches a barrel, tote, or cistern. Storing that water in a clean food-grade tank does not remove those hazards.
If rainwater is intended for drinking, treat it as a potable water system. Potable means suitable for drinking. The system may need suitable collection surfaces, debris control, first-flush management, treatment, protected storage, current laboratory testing, ongoing maintenance, and compliance with local requirements.
A first flush is a setup that diverts some of the first runoff from a roof so dirt and debris are less likely to enter storage. It can help improve incoming water quality, but it does not by itself make rainwater safe to drink.
The CDC notes that rainwater may be a water source that can be treated during an emergency, but untreated outdoor water should not simply be assumed safe.
A Simple Storage Routine
For water you fill and store yourself, a basic routine works well:
- Start with water that is already safe to drink.
- Use a clean, sanitized, food-grade container.
- Close the container tightly.
- Write the fill date on it.
- Store it somewhere cool and dark.
- Keep it away from chemicals.
- Avoid touching the water when dispensing it.
- Replace the stored water every six months.
This routine will not correct contaminated source water, but it helps protect safe water from becoming contaminated during storage.
Frequently Asked Questions
Does water expire in a plastic container?
Water does not suddenly expire, but stored water can become contaminated. For water you fill into your own container, the CDC recommends replacing it every six months. Commercial bottled water should be stored and used according to its label.
Is water stored for a year still safe to drink?
It may still appear normal, but appearance cannot establish safety. For self-filled emergency water, it is better to follow the six-month rotation recommendation rather than routinely storing the same batch for a year.
What is the best plastic container for long-term drinking-water storage?
Use a food-grade water storage container with a tight lid. A small opening or protected spigot also helps reduce the chance that hands and objects will contaminate the stored water.
Does stored water need to be refrigerated?
Not normally. Emergency water can be stored at room temperature, but it should be kept cool and away from direct sunlight. The CDC recommends a cool storage area and gives about 50°F to 70°F as a preferred range for stored household water.
Can I reuse any plastic jug for drinking water?
No. Never reuse a container that held pesticides, fuel, bleach, or other toxic chemicals. For drinking water, a purpose-made food-grade container is the safer choice.
Should I add bleach to water before storing it?
Do not add bleach automatically. If you start with safe drinking water, the important steps are using a clean, sanitized container and protecting the water from contamination. If the water itself needs disinfection, follow current drinking-water disinfection instructions because the amount used is different from the solution used to sanitize an empty container.
Can I store rainwater for six months and then drink it?
Storage time does not determine whether rainwater is potable. Roof-collected rainwater may contain germs or chemicals and should not be assumed safe to drink without an appropriate collection and treatment system, testing, maintenance, and consideration of local requirements.
