How Long Does Bottled Water Last?

There is a date stamped on the case of water in your garage, and almost everything most people believe about that date is wrong. It is not a safety deadline. It is not required by law. In most cases it is not even about the water.

Which does not mean stored water lasts forever and needs no attention. It means the things that actually degrade a water supply are different from the thing printed on the label, and if you are rotating on the date you are watching the wrong signal.

Quick Answer

The FDA does not require an expiration date on bottled water and has concluded there is no limit to its shelf life. Unopened, commercially bottled water stored properly is safe essentially indefinitely. The dates you see are voluntary: the International Bottled Water Association advises members to label a two year date for still water, and roughly one year for sparkling, as a quality and freshness marker rather than a safety one. For a practical emergency supply, plan on two years for unopened commercial bottles, and six months for water you bottled yourself, which is the CDC's replacement interval for self-filled containers. Storage conditions matter far more than the date: cool, dark, sealed, off concrete, and nowhere near gasoline or pesticides.

Key Takeaways

  • Water itself does not expire. Pure water has no nutrients to spoil and nothing to break down. Anything that goes wrong comes from the container, the seal, or what got in after bottling.
  • The date is a quality convention, not a regulation. The FDA does not require it. New Jersey was the one state that ever mandated a two year expiration date on bottled water, and it repealed that law in 2006 after finding no scientific basis for it.
  • Plastic breathes. PET bottles are permeable enough that stored water picks up odors and flavors from its surroundings over time. This is the actual mechanism behind the two year freshness guidance, and it is also why storage location matters so much.
  • Heat is the real enemy, and it is measurable. Peer-reviewed work on antimony release from PET found concentrations rising with both storage time and temperature, with elevated temperatures driving disproportionately larger increases. A hot car trunk or a sun-facing garage wall is a materially worse place to keep water than a closet.
  • Self-filled containers are a different product with a different rule. CDC guidance is to observe the printed date on store-bought water, and to replace water you bottled yourself every six months.
  • Never store water near fuel or chemicals. CDC specifically calls out keeping containers away from toxic substances such as gasoline and pesticides, because vapors permeate plastic. This is the most commonly broken rule in the average garage.

What the Date on the Bottle Actually Means

Federal rules require expiration dating on very few foods. Infant formula is the notable one. Bottled water is not on that list, and the FDA has stated that bottled water can be held indefinitely provided it is produced and packaged under the agency's good manufacturing practice rules and the seal stays intact.

So why is there a date on nearly every bottle? Three unglamorous reasons.

Freshness, meaning taste. The IBWA recommends its members apply a two year date so consumers get water that tastes the way the bottler intended. Water that has been sitting for four years in a warm room is generally safe and frequently tastes flat, plasticky, or faintly of whatever was stored beside it.

Logistics. Bottling lines already print lot codes for traceability and recalls. Adding a date costs nothing and lets retailers rotate stock with the same systems they use for everything else in the aisle.

Consumer expectation. Shoppers have been trained to distrust undated food. A bottle with no date reads as suspicious even when it is the most inert product in the store.

The practical consequence: a case of sealed water two months past its date, stored in a cool closet, is fine. A case stored six months in a hot shed is a quality question worth actually tasting before you rely on it, whether or not the date has passed.

What Actually Degrades, and How Fast

If the water is inert, the things that can change are the container, the seal, and the environment.

Permeation. PET is a good barrier, not a perfect one. Volatile compounds migrate through the wall in both directions over months and years. Water stored next to paint thinner, a running vehicle, or a bag of lawn chemicals will eventually taste like its neighbors. This is the single most underappreciated fact about home water storage, and it is the reason CDC's guidance names gasoline and pesticides explicitly rather than saying "store somewhere sensible."

Temperature. Antimony is a catalyst residue left over from making PET, and how much of it migrates into the water is governed almost entirely by heat. The numbers are specific enough to be useful, and they are covered in the next section, because this is the question people actually arrive with and it deserves more than a paragraph.

Light. Sunlight drives both warming and, where any nutrients are present at all, algal growth in translucent containers. Dark storage is free and removes the variable.

Seal integrity. Caps loosen, bottles get scuffed and punctured in a shuffled garage, and thin single-use bottles crumple under stacked weight. A compromised seal is the one failure that genuinely makes water unsafe rather than merely unpleasant, because it lets in the contamination the packaging existed to exclude.

Concrete contact. The standard advice to keep containers off a concrete floor is real, though the reason is usually misstated. It is not that chemicals leach upward out of the slab. It is that concrete stays at a different temperature than the room and wicks moisture, which encourages condensation, mold on the outside of containers, and odor transfer through the plastic. A scrap of plywood or a cheap pallet solves it.

How Hot Is Too Hot, and What the Numbers Actually Say

Ask about bottled water and plastic and you will get two useless answers: that it is perfectly fine, or that it is poisoning you. The research says something more precise and more actionable than either, which is that temperature is the variable and ordinary storage temperatures are not the problem.

The compound in question is antimony, used as a catalyst in PET manufacturing and present in trace amounts in the plastic itself. A 2014 study in the Journal of Environmental Health Science and Engineering stored five brands of bottled water at a range of temperatures and measured what came out. Antimony started at roughly one part per billion. Held at 25 degrees Celsius, about normal room temperature, it reached about 2.5 ppb after eight weeks, comfortably under the 6 ppb maximum contaminant level. Held at 65 degrees, two of the five brands exceeded that limit within two weeks. Held at 80 degrees, most exceeded it in two to three days.

A 2023 review in Molecules reached the same conclusion from the other direction: migration at refrigeration and room temperature was negligible over thirty days, and temperature was the dominant kinetic factor throughout.

Storage temperature Roughly What the research shows
4 to 20 °C Fridge to a cool room Negligible migration over a month
25 °C Ordinary room temperature Well under the limit after eight weeks
40 to 50 °C Hot attic, sunny garage wall Measurably faster, still slow in absolute terms
65 °C Closed car interior in summer sun Some brands past the limit in two weeks
80 °C Dashboard, direct sun, sealed vehicle Most samples past the limit in two to three days

Read that table for what it is. A case of water in a cool interior closet is a non-issue on any timescale you will ever store it for. A case that lives permanently in a vehicle through summer after summer is a different proposition, and the sensible response is not alarm, it is to stop storing water there. The car kit is the one place where rotating every few months genuinely matters, and it matters for this reason rather than for microbial ones.

Worth being clear about what this is not. It is not an argument that bottled water is unsafe, and it is not a reason to discard a case that spent a hot week in the garage. It is an argument that heat is the clock on plastic-bottled water, in the same way that heat is the clock on almost everything else you store.

Opened Bottles, Big Jugs, and Everything That Is Not a Sealed Half-Litre

Almost every shelf life figure quoted for bottled water assumes an unopened commercial seal. Break that seal and you are storing a different thing entirely.

An opened bottle. The moment a cap comes off, the contents are exposed to air, to whatever is on the bottle's rim, and, if anyone drank from it, to their mouth. Bacteria from a drinker's own mouth multiply in a partly drunk bottle left warm. This is not usually dangerous to the person who drank from it, and it is a genuinely bad idea to save one for the next day in a hot room and hand it to someone else. Refrigerate an opened bottle and finish it within a day or two, treat a bottle someone drank from as theirs, and do not count opened bottles as part of an emergency supply.

Five gallon jugs and water bricks. Rigid, thicker-walled, reusable containers behave better than thin single-use bottles in every respect except one: they get opened and refilled, which resets the clock and introduces whatever was on the hands and the tap. Treat a refilled jug as self-filled water on the CDC's six month replacement interval, not as commercial water on a two year date.

Fifty-five gallon drums. The mathematics are appealing and the practice usually is not. A full drum weighs over four hundred pounds, cannot be moved once filled, requires a pump to use, and concentrates the entire supply into a single point of failure that nobody rotates because rotating it means emptying four hundred pounds of water. The case against relying on one is the subject of The Water Storage Mistake Almost Everyone Makes.

The practical shape of a supply is a mix: commercial cases for the dated, sealed, grab-and-go layer, a few rigid jugs you actually rotate for bulk, and a treatment method for everything past that. Storage buys you days. A way to make more is what covers the rest.

Storage Guidance at a Glance

What you are storing Replace or rotate The reason
Unopened commercial still water, cool and dark 2 years (taste, not safety) IBWA freshness convention; FDA sets no limit
Unopened commercial sparkling water About 1 year Carbonation escapes through the closure
Water you bottled yourself in food-grade containers Every 6 months CDC guidance for self-filled containers
Any bottle stored warm, in sun, or near fuel Sooner, and taste before relying on it Heat and permeation both accelerate
An opened bottle Days, refrigerated Mouth contact introduces bacteria and nutrients
Any container with a broken seal or visible damage Discard The barrier is what kept it safe

How Much to Store

Shelf life is only half the question. The other half is whether there is enough of it.

The standard federal planning figure is one gallon per person per day, which covers drinking plus basic sanitation, with at least a three day supply for evacuation and a two week supply at home where storage space allows. Add more for children, nursing parents, anyone ill, and hot climates. Pets need their own allocation, and it is routinely forgotten until day two.

For a family of four, two weeks is 56 gallons. That is a real amount of space, which is exactly why people buy one large drum, put it in a corner, and never think about it again. That specific failure, and what to do instead, is the subject of The Water Storage Mistake Almost Everyone Makes, which also covers treatment methods and the CDC and EPA guidance behind them.

⚠️ SAFETY: If a seal is broken, a container smells wrong, the water is cloudy, or you have any reason to think stored water has been contaminated, do not drink it on the assumption that time alone made it safe. Discard it, or treat it using a method appropriate to the contamination. Boiling and chemical disinfection address microbes but not chemical contamination, and no home treatment reliably removes fuel or pesticide contamination. Verify treatment methods against current CDC and EPA guidance.

The Fuel Problem Almost Every Garage Has

Worth isolating, because it is the rule broken most often and the one most likely to quietly ruin an entire supply.

Water is heavy and bulky, so it ends up in the garage, the shed, or the basement. Those are the same places people keep gas cans for the generator and mower, paint, solvents, and lawn chemicals. Plastic water bottles are permeable to exactly the volatile organic compounds those products give off. Store the two together for a year and the water will taste like the garage, and you will not know until the day you need to drink it.

There is no treatment for this at home. Boiling does not remove it. A basic filter does not remove it. The fix is entirely preventive: put water and fuel in different rooms, or at minimum on opposite sides of the space with the fuel in sealed metal or approved containers. If you are also storing fuel for a generator, How Long Does Gasoline Last? covers keeping that supply sealed and current, which helps on both counts.

A Rotation Habit That Survives Contact With Real Life

  1. Buy dated, and store oldest in front. Ordinary grocery rotation logic, applied to the one case of goods people never think of as groceries.
  2. Write the date you stored it on the case, in marker. The printed date tells you when it was bottled. The one you write tells you when it entered your storage, which is the number that matters for a self-filled container and useful context for a commercial one.
  3. Tie rotation to a date you cannot miss. Twice a year, on the same schedule you use for smoke detector batteries and stored fuel, drink down or use the oldest stock on the garden and replace it.
  4. Taste before you trust. Once a year, open one bottle from the back of the stack. It costs nothing and it is the only test that catches slow flavor permeation, which is the failure mode no date can warn you about.
  5. Keep a treatment option regardless. Stored water is a buffer, not a permanent solution. A two week supply plus a way to make more beats a month of stored water and no plan.

FAQ

Does bottled water expire?

Not in any meaningful safety sense. The FDA does not require an expiration date on bottled water and has determined there is no shelf life limit for it. The printed date is a voluntary freshness marker, generally two years for still water on IBWA guidance. Sealed water stored cool and dark past that date is a taste question, not a safety one.

How long does bottled water last unopened?

Indefinitely from a safety standpoint if the seal is intact and it has been stored properly. For planning purposes use two years for still water and about one year for sparkling, and store it cool, dark, and away from chemicals so that quality actually holds for that long.

Is it safe to drink water that is past the date on the bottle?

Generally yes, if the bottle is sealed, undamaged, and was stored reasonably. Look at it and smell it first. Cloudiness, a compromised cap, or an off odor means discard it, and those signals are worth more than any date. Water stored somewhere hot or beside fuel deserves a taste test before you rely on it.

How often should I replace stored water?

Follow the printed date on commercially bottled water. Replace water you filled yourself every six months, per CDC guidance. Attaching that to a twice-yearly date you already observe is what makes it actually happen.

Can I store tap water in used soda or milk jugs?

Soda bottles, cleaned and sanitized thoroughly, are workable. Milk jugs are not. Milk protein and fruit sugars are extremely difficult to remove completely, they support bacterial growth, and the thin plastic of a milk jug degrades and leaks in storage. Purpose-made food-grade water containers are inexpensive and remove the guesswork.

Why does old bottled water taste strange?

Usually two things at once. Dissolved carbon dioxide escapes over time, which flattens the taste, and volatile compounds from the storage environment permeate inward through the plastic. Neither generally makes the water unsafe, and both are strong arguments for storing it away from anything with a smell.

Should I keep water bottles in the garage?

Only if the garage is cool, dark, and free of fuel and chemicals, which describes very few garages. Temperature swings accelerate degradation, and stored gasoline or pesticides will eventually taint the water through the plastic. An interior closet or a basement corner off the concrete is a better home for at least part of your supply.

Does freezing bottled water hurt it?

The water is unharmed, and frozen bottles are genuinely useful because they keep a freezer cold during an outage, which buys you time on food. Water expands about nine percent when it freezes, so leave headspace and expect some thin single-use bottles to split. Glass containers should never be frozen. How that freezer time translates into food safety is covered in How Long Does Food Last in the Fridge Without Power?.

How long does bottled water last in a hot car?

Treat a car as short-term storage and rotate it every few months. Water in a vehicle is safe to drink, but a sealed car in summer sun reaches temperatures where antimony migration from the PET stops being negligible: research found some brands exceeding the 6 ppb limit within two weeks at 65 degrees Celsius and most exceeding it within two to three days at 80. A case left in a trunk for a full year of summers is the one storage location genuinely worth being fussy about.

How long does an opened bottle of water last?

A day or two refrigerated, and treat it as finished rather than as stored water. Once the seal is broken you have introduced air and, if anyone drank from it, mouth bacteria that will multiply in a warm room. There is nothing dramatic about this, but an opened bottle is not part of an emergency supply and should not be counted as one.

Do plastic water bottles leach chemicals into the water?

In trace amounts, yes, and the amount depends almost entirely on temperature rather than on time. At refrigeration and room temperature, migration of antimony from PET is negligible over a month and stays well below regulatory limits over months. At the temperatures a closed car reaches in summer, it becomes measurable within weeks. The practical conclusion is not to avoid bottled water, it is to store it somewhere cool.

How long does a case of bottled water last one person?

A standard 24-bottle case of half-litre bottles holds a little over three gallons, which is about three days of drinking and basic sanitation for one person at the federal planning figure of one gallon per person per day. A two week supply for a family of four is roughly eighteen cases, which is why almost nobody stores two weeks entirely in cases and why the sensible supply mixes cases with larger rotated containers.

Does bottled water go bad if stored in the garage?

It can, and usually not for the reason people expect. The temperature swings matter, but the bigger risk in a typical garage is permeation: PET is permeable to the volatile compounds given off by gasoline, solvents, paint, and lawn chemicals, and water stored beside them will eventually taste like them. There is no home treatment that removes that. Keep water and fuel in different rooms and most of the garage problem disappears.

The Bottom Line

Stop treating the date on the bottle as a deadline and start treating storage conditions as the real variable, because that is what the evidence supports. Sealed commercial water kept cool, dark, off the concrete, and far away from the gas can will still be good long after its printed date. The same case stored on a sunny garage wall next to the mower fuel can be undrinkable well before it.

Two years for store-bought, six months for anything you bottled yourself, one bottle tasted from the back of the stack each year, and fuel in a different room. That is the whole discipline, and it is less work than the one big drum most people buy instead. Be prepared. Stay savage.

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