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Why Does Bottled Water Have an Expiration Date?

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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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Why Is the American Flag Displayed Backwards on Military Uniforms?
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In 1968, famed activist Abbie Hoffman decided to crash a meeting of the House Un-American Activities Committee in Washington by showing up in a shirt depicting the American flag. Hoffman was quickly surrounded by police, who ripped his shirt off and arrested him for desecration of the Red, White, and Blue.

Hoffman’s arrest is notable today because, while it might be unpatriotic to some, wearing the American flag, burning it, or otherwise disrespecting it is not a violation of any federal law. In 1989, the Supreme Court ruled that it would be unconstitutional to prosecute any such action. Still, Americans have very fervent and strict attitudes toward displaying the flag, a longstanding symbol of our country’s freedom. According to the U.S. Flag Code, which was first published in 1923, you shouldn’t let the flag touch the ground or hang it upside-down. While there’s no express prohibition about reversing the image, it’s probably a safe bet you shouldn’t do that, either.

Yet branches of the U.S. military are often spotted with a seeming mirror reflection of the flag on their right shoulder. If you look at a member in profile, the canton—the rectangle with the stars—is on the right. Isn’t that backwards? Shouldn’t it look like the flag on the left shoulder?

The American flag appears on a military uniform
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Not really. The flag is actually facing forward, and it’s not an optical illusion.

When a service member marches or walks forward, they assume the position of a flagpole, with the flag sewn on their uniform meant to resemble a flag flapping in the breeze. With the canton on the right, the flag would be fluttering behind them. If it were depicted with the canton on the left, the flag would be flying backward—as though it had been hung by the stripes instead of the stars nearest to the pole. The position of the flag is noted in Army Regulation 670-1, mandating the star field should face forward. The official term for this depiction is “reverse side flag.”

As for Hoffman: His conviction was overturned on appeal. In 1970, while at a flag-themed art show in New York, he was invited to get up and speak. He wore a flag shirt for the occasion.

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What Causes Sinkholes?
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This week, a sinkhole opened up on the White House lawn—likely the result of excess rainfall on the "legitimate swamp" surrounding the storied building, a geologist told The New York Times. While the event had some suggesting we call for Buffy's help, sinkholes are pretty common. In the past few days alone, cavernous maws in the earth have appeared in Maryland, North Carolina, Tennessee, and of course Florida, home to more sinkholes than any other state.

Sinkholes have gulped down suburban homes, cars, and entire fields in the past. How does the ground just open up like that?

Sinkholes are a simple matter of cause and effect. Urban sinkholes may be directly traced to underground water main breaks or collapsed sewer pipelines, into which city sidewalks crumple in the absence of any structural support. In more rural areas, such catastrophes might be attributed to abandoned mine shafts or salt caverns that can't take the weight anymore. These types of sinkholes are heavily influenced by human action, but most sinkholes are unpredictable, inevitable natural occurrences.

Florida is so prone to sinkholes because it has the misfortune of being built upon a foundation of limestone—solid rock, but the kind that is easily dissolved by acidic rain or groundwater. The karst process, in which the mildly acidic water wears away at fractures in the limestone, leaves empty space where there used to be stone, and even the residue is washed away. Any loose soil, grass, or—for example—luxury condominiums perched atop the hole in the ground aren't left with much support. Just as a house built on a weak foundation is more likely to collapse, the same is true of the ground itself. Gravity eventually takes its toll, aided by natural erosion, and so the hole begins to sink.

About 10 percent of the world's landscape is composed of karst regions. Despite being common, sinkholes' unforeseeable nature serves as proof that the ground beneath our feet may not be as solid as we think.

A version of this story originally ran in 2014.

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