Closeup on mineral water bottles in raw and lines

How Long Does Bottled Water Last When Stored?

Amidst an ongoing pandemic and multiple weather-related crises, many people have stocked up on bottled water within the past couple of months.  Like many items on grocery store shelves, bottled water does go bad over time and some people may be unaware of this.

Because bottled water companies are technically allowed to go without listing an exact expiration date on their products, you should know how soon water goes bad and how to properly store it in order to keep it from spoiling early.

Does Bottled Water Expire?

Bottled water isn’t necessarily the kind of product that you’d expect to go bad over time.  However, bottled water does have a relative shelf life and does expire after a certain amount of time in storage. Bottled waters expire because, after so much time in storage, they become more vulnerable to contamination.

Some forms of contamination can cause health problems in humans and other animals.  Once bottled water expires, the risks of contamination are too high and you should avoid drinking it. Perhaps the reason some people are unaware of bottled water expiry is that the US Food and Drug Administration (FDA), which is in charge of food safety in America, does not require bottled water companies to list an explicit expiration date on their products. 

It does have other standards in terms of how water must be purified and filtered, but it does not have a standard for expiration.  As a result, most bottled water companies don’t list an expiration date on their water but rather a “best before” date.  A best before date is more of an indicator of water quality than safety, though.  The ambiguity of both the FDA standards and the date listed on the bottled water is enough to cause plenty of confusion.

The most typical best before date on bottled water is:

  • 24 months after purchase (for still water)
  • 12 to 18 months after purchase (for sparkling water)

While these aren’t necessarily expiration dates, they are the closest thing to a measure of an expiration date that we have right now.  Therefore, at least for now, you can consider the best before date as the expiration date of bottled water given that it is stored properly. 

Additionally, in order for bottled water to stay fresh up until its best before date, it should be stored properly and remain unopened.  If you fail to keep your bottled water stored properly or open it before drinking, it will most likely go bad before the best before date. 

So, according to many bottled water companies, drinking bottled water within 2 years of purchasing it is what’s best to avoid contamination.  This may or may not be an exact expiration date but is a fair standard to go by considering the FDA doesn’t have a whole lot of guidance on the matter.  Therefore, if you have emergency water in storage that has been there for more than 2 years now, you might want to consider disposing of it.

Does Bottled Tap Water Expire?

Just like regular bottled water, bottled tap water stored in reusable water bottles has become more popular in recent years.  Sales of reusable water bottles have exploded since 2010 and by 2025, the value of the market is expected to reach almost 11 billion dollars.

Bottled tap water stored in reusable bottles has a shelf life of about 6 months.  Tap water is prone to similar types of contamination that store-bought bottled water is.  Also, like a store-bought bottled water, in order to maximize the shelf life of your bottled tap water, it is essential to store it properly and keep it unopened. 

Potential Health Hazards of Expired Bottled Water

The dangers regarding drinking expired bottled water are less about the water and more about the plastic bottle itself.  As bottled water sits over time, the plastic bottle deteriorates and contaminates the water.  Whether or not the bottled water was stored properly can make the contamination start sooner or make the contamination worse.

Some of the ways in which bottled water can become contaminated and result in expiration include:

  1. Microplastics and plastic chemical contamination
  2. Algae growth
  3. Household chemical contamination

If you store your bottled water properly, it should live out its full shelf life.  However, regardless of whether the bottle was stored properly or not though, eventually all bottled water needs to be disposed of upon expiration to ensure safety. 

girl drinks polluted water microplastic

A study by OrbMedia found that over 80% of all samples analyzed (taken from tap and bottled water) contained tiny plastic particles.

Microplastics and Plastic Chemical Contamination

First off, the most common and well-known way in which bottled water becomes contaminated and thus requires an expiration date is because of plastic contamination.  The longer that water sits in the plastic bottle, the more likely it is to become contaminated by the plastic.  Expiration dates remind you to drink the water before the plastic contaminates the water to the point that it would get you sick.

Plastic can contaminate your bottled water in a couple of ways including:

  • Microplastics
  • Polyethylene terephthalate chemicals
  • BPA chemicals

Microplastics

First off, while you may think that your fresh bottled water looks clean, certain scientific evidence would say it is actually quite dirty.  According to one recent study measuring microplastic contamination in bottled water, it found that 93% of bottled waters tested positive for excessive amounts of microplastics.  For every liter of bottled water sold on average, they found that it contained 325 particles of microplastics.

Microplastics are tiny pieces of plastic measuring less than 5 millimeters in length.  They make their way into our water, air, and soil from countless different pollution-causing human activities including:

  • Fishing and agriculture
  • Clothing manufacturing 
  • Packaging and shipping

Plastic pollution is pervasive and you can never fully escape the effects of it.  Because so little plastic is recycled and takes years to decompose, it pollutes entire ecosystems and makes its way into not only your bottled water, but also your food, tap water, and even the air you breathe.

While research on the health effects of ingesting microplastics is still fairly new, the results so far are not looking good.  In recent years, research regarding the effects of ingesting microplastics has shown increased risks of developing:

  • Metabolic diseases
  • Cancer
  • Neurological disorders
  • Reproductive issues
  • ADHD

Considering that the research regarding microplastic implications on health is still fairly new and already looks very grim, you could say that things aren’t off to a good start. 

Plastic Chemical Contamination: BPA and Polyethylene Terephthalate

In addition to dangers associated with ingesting microplastics, plastic itself can have toxic effects on your body when it contaminates water.  Two common plastic chemicals known to cause water contamination are bisphenol A (BPA) and polyethylene terephthalate (PET).

First off, BPA has become widely known over the past few years for all the wrong reasons.  BPA is what’s known as an endocrine disruptor, a chemical that mimics or interferes with the human body’s natural hormone system.  Exposure to endocrine-disrupting chemicals including BPA can cause health problems including:

  • Weakened immune system 
  • Disruption of metabolism
  • Delayed puberty
  • Reproductive challenges
  • Attention disorders

You can be exposed to BPA and other endocrine-disrupting chemicals through bottled water, plastic containers, pesticides, and more.  You can ingest them, breathe them in, or even be contaminated by mere skin contact.  In bottled water specifically, BPA gets into the water by leaching out of the plastic bottle.  As a result, the water becomes contaminated with the endocrine-disrupting chemical.  Therefore, it is extremely important that you don’t drink bottled water after its best before date.

Second, PET is one of the most common substances used to make plastics today.  It is used to make plastic bottles, bags, containers, toys, clothes, and more.  It is commonly referred to as a safer form of plastic as it is BPA-free.  However, recent research has shown that PET may also be an endocrine disruptor, just like BPA.  Therefore, it could be just as dangerous to your health.

Overall, exposure to either BPA or PET could cause contamination as it seeps into your water.  While BPA is already a well-known endocrine disruptor, PET could also be just as dangerous.  You can avoid plastic chemical contamination from both BPA and PET by drinking your water before its best-before date. 

Algae Growth

algae-growth

Another common way in which your bottled water can become contaminated is through toxic algae growth. You may typically associate algae with green scum forming around the rim of your yard’s pond or fountain.  However, it can also grow in your water plastic and reusable water bottles as well. In order for algae to grow, it needs a few resources including:

  1. Nutrition
  2. Sunlight
  3. Warmth
  4. Carbon dioxide

For starters, algae needs nutrition.  Its favorite nutrients include phosphorus and nitrogen; both are commonly found in bottled water and tap waters that haven’t been thoroughly decontaminated.  Then, it requires sunlight, warmth, and carbon dioxide to keep growing.  If all of these resources are present, then algae can grow in water regardless of if it’s in a lake, pond, or water bottle.

Algae growth within water bottles expedites the expiration of the water.  Once algae starts to form in the water, you should not drink it as algae can cause different health problems including:

  1. Headaches
  2. Vomiting
  3. Respiratory issues

If you see algae growing in your bottled water, consider it expired and undrinkable.  But, you can easily prevent algae growth in the first place if you remove your bottles of water from an environment that fosters algae growth.  That means keeping your water out of direct sunlight, keeping the caps closed, and making sure that they don’t sit in locations warmer than room temperature.  If you follow these conditions, algae growth is easily preventable. 

Household Chemical Contamination

A third way in which your bottled water can get contaminated and expire sooner is through contamination from household chemicals. Plastic water bottles are slightly permeable, meaning that very tiny particles can seep through them and infiltrate the water. Some of the most common contaminating particles that seep through plastic bottled include those found in your home’s cleaning products.  \

Basic household cleaners, bleach, and detergent are all toxic to humans and can seep through plastic bottles. Therefore, it is important that you store your plastic water bottles away from any of these chemicals, especially if they are in spray bottles.  The closer you keep your household chemicals to your water supply, the easier it is for them to contaminate the water.

How to Tell if Your Bottled Water Has Expired

In addition to bypassing the best before date, there are a couple of other signs which could indicate that your water is expired and unsafe for you to drink.  The most common ones include:

1. Color and clarity: First off, bottled water that is fresh and not expired should be clear and virtually colorless.  On the other hand, bottled water that has expired may have a slight color tint to it or be less clear.  If your water develops a color or loses its clarity while sitting in storage for a while, then do not drink it. 

2. Odor: Second, bottled waters that haven’t yet reached their expiration date should generally be odorless.  Most bottled waters, particularly purified ones, are thoroughly filtered and decontaminated to remove most of their smells.  Therefore, if the bottled water starts smelling, it could be a sign of expiration.  Watch out for any rotten egg or sulfur-like smells in particular.

3. Taste: Lastly, unusual tastes in bottled water are another clear sign that it could be expired and contaminated.  If you drink bottled water and it has an off-putting taste, then stop drinking it and throw it out.

Big plastic bottles with water on the table

It’s a good idea to keep bottled water away from direct sunlight and at room temperature.

How to Store Bottled Water Safely

While bottled water usually doesn’t expire for 2 years after purchase, improper storage could speed up the time in which the water expires.  Therefore, in order to have the longest shelf life possible, follow these water storage guidelines to maintain the longevity of your plastic bottled water.

1. Store Water in a Room Temperature Location

The first thing you can do to prevent your bottled water from going bad is to keep it in a room-temperature location.  Bottled water that is stored at warmer than room temperature is more prone to:

  • Algae and mold growth
  • Chemical contamination from plastic bottle deterioration

To avoid both algae growth and plastic chemical contamination, keep your bottled water in a cool location

2. Do Not Open Water Bottles Before Drinking

Next, one of the simplest ways to make bottled water go bad is to open the caps up before drinking the water.  Opening up the caps allows germs and bacteria to get into the water before you drink it.  Simply put: Don’t open up the bottles of water until you are ready to drink them.

3. Regularly Move the Water Bottles

Prevent your unopened bottles from developing algae or mold by keeping the water from going stagnant for long periods of time.  Stagnant water is more likely to foster environments that promote the growth of contaminants, so you should regularly shake or move around your unopened bottled water to prevent any invader from growing.

4. Keep Water Bottles Out of Direct Sunlight

Lastly, prevent your water from expiring early by keeping the bottles in a dark place.  Sunlight and other light sources not only heat up the water but provide the necessary light needed to help fuel algae growth.  The best place to store bottled water is a dark closet, pantry, or basement.

Bottom Line: Keep Your Bottled Water Safe

In conclusion, to avoid a water contamination situation, consider your bottled water expired after 2 years of purchasing it.  While the FDA and bottled water companies aren’t very clear on when bottled water expires, follow the best before date in order to avoid potential health risks due to contamination.  

You can prevent expediting expiration by taking certain steps to prevent early contamination such as proper storage.  Overall, as long as your water remains unopened, is regularly moved around, and is stored in a cool, dark place, then you should feel at ease drinking it before its best-before date. 

Bonus tip: If you don’t enjoy the bland taste of water and struggle to drink enough water on a daily basis, consider giving flavored bottled waters such as Hint Water a chance.  They’re tasty, high in minerals, and help keep you hydrated just like traditional bottled water.

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Joshua Perkins

Joshua spent ten years as a water systems technician in California before settling down with his wife and two young children in Nashville in 2018. Through all of his experience, he learned the benefits and shortfalls of so many different types of water filtration systems, from pitchers to whole-house installations. He started Water Filter Authority in 2019 to empower other families to make the right decision for their long-term health and wellness.