If you’ve left the house for an extended period of time—whether for vacation or a major weather event like a storm evacuation—there’s a chance you might return to a home without power. Usually it’s easy to tell which food has spoiled in your fridge, but when it comes to the freezer, anything goes.

Nobody wants to waste time and money in situations like these. Luckily, there’s an easy way to determine if your frozen food is safe to eat—and all you need is a mug, water, and a coin!

Before you leave your house unoccupied for a number of days, whether for a vacation or a weather emergency, freeze a mug full of water. Once it’s solid, place a coin on top of the ice.

1-frozen-coin-trickFacebook / Sheila Pulanco Russell

When you return, check the coin. If it became so warm—i.e. you lost power for so long that the freezer heated up significantly—and the coin sunk to the bottom of the mug, you can reasonably assume your food has gone bad and must be thrown away. If the coin remains at the top or middle of the mug, the food should still be safe to eat!

Sheila Pulanco Russell, who came up with this trick and shared it with her friends on Facebook, suggests doing this “all the time” just in case anything ever happens to your power. “If you don’t feel good about your food, just throw it out,” she explains. “The main thing is for all to be safe.”

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