Is it bad to drink old opened bottled water?

Quick Answers

It’s generally not recommended to drink bottled water that has been opened for a long time. Bacteria and other microbes can grow inside the bottle over time. How long the opened bottled water stays fresh depends on several factors like the initial quality of the water, how it was stored, and the temperature. As a general rule, opened bottled water should be consumed within 6 months if kept refrigerated, and within a few days if left at room temperature.

How Long Does Unopened Bottled Water Last?

Unopened, commercially bottled water typically stays fresh and safe to drink indefinitely, as long as the bottle remains properly sealed. This very long shelf life can be attributed to:

  • Purification methods used by most bottled water companies which remove bacteria and other microbes.
  • Lack of air inside the sealed bottle prevents oxidative reactions.
  • Plastic bottles help prevent external contaminants from getting inside.

So as long as the plastic seal remains intact, bottled water can theoretically last forever without going bad. Having said that, some changes in taste may be observed after several years due to the breakdown of some organic compounds or leaching of chemicals from the plastic bottle.

Why Does Opened Bottled Water Go Bad?

Once opened, bottled water comes in contact with oxygen and microbes present in the air and environment. This leads to some chemical and microbial changes that can cause the water to deteriorate over time:

  • Exposure to air and light accelerates breakdown of organic compounds and leaching of chemicals from the plastic bottle material. This can lead to some changes in taste and odor.
  • Bacteria, mold and other microbes can enter through the mouth of the bottle and start multiplying if the water contains enough nutrients to support their growth.
  • Plastic bottles are porous and small amounts of air and microbes can eventually diffuse through over time once opened.

So opened bottled water lacks the long-term shelf life of unopened water. Consumption becomes riskier after the water sits for too long after opening.

How Long Does Opened Bottled Water Last?

An opened bottle of water should ideally be consumed within:

  • 6-12 months – If refrigerated
  • 2-7 days – If left at room temperature
  • 24 hours – If bottle was completely empty before being refilled from the tap

Proper refrigeration slows down microbial growth and oxidation reactions, allowing opened bottled water to stay potable for about 12 months. But some experts consider 6 months a safer cutoff. If left unrefrigerated, rapid deterioration makes room temperature water unsafe beyond a week.

Refilling an empty disposable bottle is very risky since the plastic is highly porous. Such water should not be kept longer than a day.

Factors Affecting Opened Bottle Shelf Life

How long an opened water bottle stays fresh also depends on these key factors:

  • Initial Water Quality – Higher quality water from protected springs or municipal supplies lasts longer than low-grade tap water which contains more nutrients for microbial growth.
  • Storage Temperature – Refrigeration below 40°F preserves opened water much longer compared to room temperature storage.
  • Air Exposure – Repeatedly re-opening and closing the bottle allows more airborne microbes and oxygen to enter and degrade quality.
  • Bottle Material – Glass bottles are less porous than plastic ones, preventing air diffusion and leaching of chemicals.

Proper refrigeration in glass bottles maximizes opened bottle shelf life. Storing disposable plastic bottles at room temperature significantly reduces it.

How to Tell If Opened Bottled Water Has Gone Bad

Signs that opened bottled water has gone bad and may not be safe for consumption include:

  • Cloudiness – Particulate matter or microbial growth causes the water to appear hazy.
  • Changes in smell and taste – Due to chemical changes or microbial growth. A musty or rotten smell indicates advanced degradation.
  • Microbial contamination – Visible mold/algae indicates bacteria, fungi and other microbes proliferating due to nutrients in old water.
  • Bottle bloating and leakage – Gas produced by microbial growth pressurizes the bottle.
  • High bacterial counts – Coliforms and other microbial indicators exceeding safety limits make the water unfit to drink.

If opened bottled water shows the above signs, it is best to discard it instead of taking a chance. The plastic bottle itself may also show cracks, clouding or become brittle if the water is extremely old.

Can Drinking Old Bottled Water Make You Sick?

Yes, drinking bottled water that has been open too long can cause illness in some cases due to:

  • Chemical Contaminants – Leached phthalates, antimony, bromine and other chemicals from bottles. More likely in older plastic bottles.
  • Heavy Metals – Lead, arsenic, cadmium, etc. leached from pipes and plumbing during initial bottling/processing.
  • Microbes – Disease-causing bacteria, viruses, protozoa etc. entering through mouth of bottle and multiplying over time.
  • Toxins – Microcystin, anatoxins and other toxins produced by cyanobacteria and molds growing in nutrient-rich old water.

Symptoms from ingesting such contaminated water range from gastrointestinal distress to neurological issues, organ damage, infections and even cancer on long-term exposure.

At-Risk Groups

The following groups face higher risk for illness from drinking old bottled water:

  • Infants and young children
  • Pregnant women
  • Elderly people
  • Those with weakened immune systems
  • People with chronic illnesses

Healthy adults may be able to tolerate lower levels of contamination. But at-risk groups could experience severe complications from even small amounts of bacteria, toxins or other substances in water gone bad.

How To Store Bottled Water Properly

Follow these tips to maximize freshness and shelf life of bottled water after opening:

  • Refrigerate after opening – Keep unused portions chilled below 40°F.
  • Minimize air exposure – Cap tightly and limit reopening number of times.
  • Avoid storage near natural light – Keep bottles in dark pantry or fridge.
  • Use before expiration date – Though water itself doesn’t expire, consume within 2 years of bottling.
  • Check for bottle damage – Don’t drink from bottles that are cracked, cloudy or misshapen.
  • Don’t reuse disposable bottles – Throw away disposable plastic bottles after use.

Proper refrigeration and minimal air exposure helps slow deterioration and microbial growth, keeping opened bottled water potable for longer.

Can Old Bottled Water Be Used Safely?

If the bottled water shows signs of deterioration in taste/smell or you’re unsure of its age, avoid drinking it. However, old opened bottled water may still be used safely for these purposes if it appears clear with no odors:

  • Watering houseplants
  • Filling pet water bowls
  • Cleaning surfaces
  • Washing fruits and vegetables
  • Cooking food like pasta
  • Making coffee, tea etc. where water is boiled

The heat from cooking or boiling water kills any bacteria present. And for non-consumption uses, mild microbial contamination poses little risk. Just don’t use dubious water for drinking, ice cubes, baby food preparation etc.


Can old bottled water make you vomit?

Yes, drinking bottled water that has gone bad can cause vomiting along with nausea, diarrhea, cramps and other gastrointestinal issues. The source is usually pathogenic bacteria like E.coli, Salmonella, Clostridium etc. that have multiplied in old water not stored properly after opening.

Can you drink bottled water 2 years out of date?

It’s not recommended to drink bottled water more than 12-18 months after the bottling date, even if unopened. Beyond 2 years, chemical leaching from the plastic and microbial growth even through unopened seals becomes highly likely. The water may appear fine but contain dissolved phthalates and other contaminants.

Does unopened bottled water expire?

No, commercially bottled water in properly sealed original containers does not really expire. If stored in a cool, dark place, it can last indefinitely while remaining fresh and safe. However, many brands print ‘best by’ or ‘sell by’ dates 2-3 years from bottling as the optimal duration for peak flavor and chemical stability.

Can old plastic water bottles cause cancer?

No direct evidence shows old bottles alone can cause cancer. But very old, degraded plastic bottles may leak chemicals like antimony, BPA and phthalates into the water, especially if exposed to heat or sun. Some of these compounds are considered potentially carcinogenic to humans after long-term oral exposure.

Does freezing water in plastic bottles make it last longer?

Freezing helps better preserve opened bottled water compared to room temperature storage. It stops microbial growth and slows chemical leaching. However freezing can make plastic bottles brittle and prone to cracking. Filling only 3/4th of the bottle allows expansion of water during freezing. Frozen water in intact bottles can last 6-12 months stored this way.


Drinking old stored bottled water is generally deemed safe for up to 6-12 months if refrigerated after opening. However, it may not be advisable for vulnerable groups even within this duration. Visual and smell inspections for cloudiness, particulates and off-odors can further indicate deterioration. Practicing proper storage methods like minimizing air exposure and refrigeration helps maximize shelf life. While opened bottled water does eventually go bad with time, following some simple guidelines allows prolonging its freshness and potability.

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