BOTTLED WATER - Does Bottled Water Go Bad? - Although bottled water has an expiration date, it doesn't actually go bad. Your water may carry an expiration date to make it easier to standardize packaging. Some bottled water only carries its bottling date or a "best by" date. These dates are helpful because the flavor of the water will change over time as it absorbs chemicals from its packaging. The flavor will not necessarily be bad, but it may be noticeable. A plastic taste is not necessarily an indicator that the water is bad; conversely, the absence of an unpleasant flavor does not mean the water is free from contaminants.

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Bottled Water

Does Bottled Water Go Bad?

by Anne Marie Helmenstine, Ph.D. 

Most bottled water has an expiration date stamped on the bottle, but does the bottled water actually go bad?

If so, how long is bottled water good? The answer to this common question is fairly simple.

Expiration Dates Come From a State Law

Although bottled water has an expiration date, it doesn't actually go bad. Why is there an expiration date on a product that doesn't go bad?

This is because the state of New Jersey requires all food and beverages, including water, to carry an expiration date on its packaging.

It doesn't matter if you don't live in New Jersey... your water may carry an expiration date anyway to make it easier to standardize packaging.

Some bottled water only carries its bottling date or a "best by" date.

These dates are helpful because the flavor of the water will change over time as it absorbs chemicals from its packaging. The flavor will not necessarily be bad, but it may be noticeable.

Any Leaching From Plastic Is Unrelated to Time

Leaching of chemicals from packaging is a health concern, but as far as toxic chemicals go, you can get exposure to most of those chemicals from freshly bottled water as well as bottled water that has been on the shelf a while.

A plastic taste is not necessarily an indicator that the water is bad; conversely, the absence of an unpleasant flavor does not mean the water is free from contaminants.

Keep Bottled Water Sealed

While algae and bacteria will not grow in sealed bottled water, the situation changes once the seal has been broken.

You should consume or discard water within two weeks after opening it.

Anne Marie Helmenstine, Ph.D.

Introduction

Ph.D. in biomedical sciences from the University of Tennessee at Knoxville - Oak Ridge National Laboratory.

Science educator with experience teaching chemistry, biology, astronomy, and physics at the high school, college, and graduate levels.

ThoughtCo and About Education chemistry expert since 2001.

Widely-published graphic artist, responsible for printable periodic tables and other illustrations used in science.

Experience

Anne Helmenstine, Ph.D. has covered chemistry for ThoughtCo and About Education since 2001, and other sciences since 2013. She taught chemistry, biology, astronomy, and physics at the high school, college, and graduate levels. She has worked as a research scientist and also abstracting and indexing diverse scientific literature for the Department of Energy.

In addition to her work as a science writer, Dr. Helmenstine currently serves as a scientific consultant, specializing in problems requiring an interdisciplinary approach. Previously, she worked as a research scientist and college professor. 

Education

Dr. Helmenstine holds a Ph.D. in biomedical sciences from the University of Tennessee at Knoxville and a B.A. in physics and mathematics with a minor in chemistry from Hastings College. In her doctoral work, Dr. Helmenstine developed ultra-sensitive chemical detection and medical diagnostic tests.

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https://www.thoughtco.com/does-bottled-water-go-bad-607370