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Tonic Water

Fancy tonic waters abound. Do you need one to make a good gin and tonic?


Published May 29, 2019.

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What You Need To Know

As its name implies, tonic water was originally used as a curative. In 19th-century India, where malaria was rampant, quinine, an alkaloid extracted from the bark of the cinchona tree, was the primary means for both preventing and treating the disease. Like all alkaloids, quinine is intensely bitter, so British colonists diluted it with carbonated water, forming a tonic. Later, they improved this tonic's flavor by adding sweeteners and other flavoring agents. It was only a matter of time before gin, England's favorite tipple, was incorporated as well.

These days, tonic water is no longer drunk for its medicinal value. In fact, the U.S. Food and Drug Administration now limits the quinine content in tonic water to 83 parts per million; larger doses, while therapeutic for malaria, can actually increase the risk of other health problems. Still, in the time since tonic water was first produced, people around the world have developed a taste for its unique flavor and effervescence. If anything, the popularity of tonic water is on the rise, with more companies than ever developing interesting new formulations of this classic beverage. Curious to know which tonic water was best, we tasted eight nationally available products, priced from about $0.05 to about $0.30 per ounce—four supermarket brands and four artisanal brands, all nationally available—plain and in gin and tonics.

A Little Bitterness is Important

As it turned out, our panel liked most of the tonic waters we tried; finding them all acceptably fizzy. Tasters' ratings varied, however, depending on the flavor of the tonic.

Not surprisingly, considering the historic use of quinine as a flavoring agent, tasters expected and preferred tonic waters that were moderately bitter. Too much bitterness, as in our two least favorite products, was “off-putting,” making for “strange, sharp, astringent” tonics. Too little bitterness, on the other hand, made for tonic water that was palatable but “not very memorable” and a bit “bland” both plain and in a gin and tonic. Overall, tasters liked tonic waters that were “slightly bitter” but not “overpowering.”

Wondering if the differences in bitterness were due to differences in the amounts of quinine used, we dug a little deeper. Quinine is fluorescent, so we used a black light to illuminate each product to see if there were any differences in how brightly they shone. All the products glowed brightly except one—the product that tasters thought had “no bitterness.” This tonic barely lit up under the black light, indicating that it contained significantly less quinine than the others. The two very bitter products, by contrast, shone just as brigh...

Everything We Tested

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The mission of America’s Test Kitchen Reviews is to find the best equipment and ingredients for the home cook through rigorous, hands-on testing.

Miye Bromberg

Miye is a senior editor for ATK Reviews. She covers booze, blades, and gadgets of questionable value.