Why Does Bottled Water Have an Expiration Date?

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iStock

Expiration dates on non-perishable consumer goods are a funny thing. Few people need an explanation as to why meat or dairy products have a sell-by date, but other things seem to demand a little more context. Child car seats, for example, have an expiration date because safety regulations change on a regular basis and because they can experience wear after years of daily use.

A date stamped on bottled water, however, seems to defy all laws of common sense. Shouldn't H2O technically be good forever?

The answer is yes—but water quality isn't the issue. A 1987 New Jersey state law required all food products sold there to display an expiration date of two years or less from the date of manufacture. Labeling, separating, and shipping batches of expiration-dated water to the Garden State seemed a little inefficient to bottled water producers, so most of them simply started giving every bottle a two-year expiration date, no matter where it was going.

The U.S. Food and Drug Administration has never established or suggested a limitation on the shelf life of bottled water as long as it's produced in accordance with regulations and the bottle remains properly sealed. New Jersey caught on to this fact and amended the law, but the expiration date has been an industry norm for so long that many producers have just kept it on there.

While "expired" unopened bottled water isn't going to do you any harm, it isn't going to get better with age, either. The plastic that water is packaged in—usually polyethylene terephthalate (PET) for retail bottles and high-density polyethylene (HDPE) for water cooler jugs—may begin leaching into the liquid, affecting its taste. It's also slightly porous, so the water can pick up smells and other unwelcome additives from the outside world. The odds of a five-year-old bottle of Evian harming you are virtually nonexistent, but if it's been stored in your basement, you might be better off reaching for a fresher bottle.

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What is a Polar Vortex?

Edward Stojakovic, Flickr // CC BY 2.0
Edward Stojakovic, Flickr // CC BY 2.0

If you’ve turned on the news or stepped outside lately, you're familiar with the record-breaking cold that is blanketing a lot of North America. According to The Washington Post, a mass of bone-chilling air over Canada—a polar vortex—split into three parts at the beginning of 2019, and one is making its way to the eastern U.S. Polar vortexes can push frigid air straight from the arctic tundra into more temperate regions. But just what is this weather phenomenon?

How does a polar vortex form?

Polar vortexes are basically arctic hurricanes or cyclones. NASA defines them as “a whirling and persistent large area of low pressure, found typically over both North and South poles.” A winter phenomenon, vortexes develop as the sun sets over the pole and temperatures cool, and occur in the middle and upper troposphere and the stratosphere (roughly, between six and 31 miles above the Earth’s surface).

Where will a polar vortex hit?

In the Northern Hemisphere, the vortexes move in a counterclockwise direction. Typically, they dip down over Canada, but according to NBC News, polar vortexes can move into the contiguous U.S. due to warm weather over Greenland or Alaska—which forces denser cold air south—or other weather patterns.

Polar vortexes aren't rare—in fact, arctic winds do sometimes dip down into the eastern U.S.—but sometimes the sheer size of the area affected is much greater than normal.

How cold is a polar vortex?

So cold that frozen sharks have been known to wash up on Cape Cod beaches. So cold that animal keepers at the Calgary Zoo in Alberta, Canada once decided to bring its group of king penguins indoors for warmth (the species lives on islands north of Antarctica and the birds aren't used to extreme cold.) Even parts of Alabama and other regions in the Deep South have seen single-digit temperatures and wind chills below zero.

But thankfully, this type of arctic freeze doesn't stick around forever: Temperatures will gradually warm up.

In What Field Was Dr. Martin Luther King, Jr. a Doctor?

Express Newspapers/Getty Images
Express Newspapers/Getty Images

Martin Luther King, Jr. earned a doctorate in systematic theology from Boston University in 1955. He’d previously earned a Bachelor of Arts from Morehouse College and a Bachelor of Divinity from Crozer Theological Seminary. His dissertation, “A Comparison of the Conception of God in the Thinking of Paul Tillich and Henry Nelson Wieman,” examined the two religious philosophers’ views of God in comparison to each other, and to King’s own concept of a "knowable and personal" God.

Some three decades after he earned his doctorate, in 1989, archivists working with The Martin Luther King Papers Project discovered that King’s dissertation suffered from what they called a “problematic use of sources.” King, they learned, had taken a large amount of material verbatim from other scholars and sources and used it in his work without full or proper attribution, and sometimes no attribution at all.

In 1991, a Boston University investigatory committee concluded that King had indeed plagiarized parts of his dissertation, but found that it was “impractical to reach, on the available evidence, any conclusions about Dr. King's reasons for failing to attribute some, but not all, of his sources.” That is, it could have been anything from malicious intent to simple forgetfulness—no one can determine for sure today. They did not recommend a posthumous revocation of his degree, but instead suggested that a letter be attached to the dissertation in the university library noting the passages lacked quotations and citations.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

This article was originally published in 2013.

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