THE MARCH IS ENDLESS; your sandals chafe your feet. Your column of soldiers stretches in front of you like a serpent, undulating left-right-left as hundreds of heads bob up and down in the Mediterranean sun. You don’t really know where you’re going, but you don’t care anymore — everywhere is the empire now, so no matter how far you walk, you never leave the shadow of Rome.

And you’re thirsty. The road is choked with dust and animal dung, and you’ve been wetting your tongue on the sweat dripping down your face for the past 2 miles. So when the centurion suddenly signals to stop and make camp, all you can think of is that in moments, you will be handed a cup of delicious, warmish-but-refreshing, thirst-slaking, lip-wetting, life-reviving … vinegar.

Drinking vinegar is like so many other things we moderns think we invented that the Romans already had mastered thousands of years ago. The Roman drinking vinegar, or posca, was made from acetum, a slightly alcoholic byproduct of winemaking (in truth, it was mostly just wine that had gone off).

In a world where the drinking water was often a hazard, diluted vinegar could hydrate an entire army. Frequently referred to as the “Gatorade of the Roman World” by the cheeky BBC writers of today, posca, which was only faintly alcoholic, was often mixed with herbs for flavoring and probably tasted like heavily watered-down salad dressing.

You might think this sounds unappealing, but check the cold case of your closest Whole Foods or PCC, and you will find many forms of suddenly trendy drinking vinegar. There is something for everyone: Clean-eaters can quench their thirst with “vinegar tonics,” and discerning cocktail aficionados can perk up their quaffs with small-batch shrubs (sweetened, reduced, vinegar-based syrups that often replace soda or juice in your finer libations).

There is a whole host of health claims made for drinking vinegar, and apple cider vinegar in particular long has been considered a panacea, credited variously with clearing up acne, aiding weight loss, lowering cholesterol and destroying cellulite, among other things.

Most commercial drinking vinegars have some added sugar, so they’re a lot more pleasant than sucking down straight ACV, and they taste quite a bit like kombucha, though they are not actually probiotic. None of those health claims has been definitively proved, but anecdotally, I can tell you this: As a person who prefers my cocktails tangy, I find drinking vinegars and shrubs the best mixers in the world.

Companies like Seattle’s The Shrubbery (extra points for the name) make their small-batch drinking vinegars in flavors like peach brown sugar and Strawberries ’n’ Champagne, and Rocco’s in Belltown and Canon near Seattle University will craft you some cocktails with fruity/spicy shrubs designed to complement the food. And if you have a long hike up Mount Rainier coming up and want to do like the Romans did, here is a possibly accurate-ish posca recipe: