What Is Tonic Water? A Bitter Explainer

Have you ever ordered a delicious gin and tonic, taken a sip, and wondered, “What the heck is tonic, anyway?” Good for you for questioning the things you ingest—albeit a little late. It’s a valid question. What exactly is tonic water? What’s in tonic water that makes it different? What’s up with all those different bubbly waters and is there a difference between carbonated water, club soda, and tonic water? Don’t worry, we’ll answer all your questions so you can stop questioning your choices and feel good about taking that next sip.

What is tonic water?

Tonic water is a bitter, carbonated soft drink made with quinine and some sort of sweetener. It’s often used as a mixer. What does all that mean? The main difference between tonic water and other carbonated water drinks is its dry bitterness. Why is it like that? What’s in tonic water? That element comes from quinine. Quinine is a medication that is used to treat malaria and comes from the bark of a cinchona tree, which Native people in Peru and throughout Central America used to treat ailments. The Jesuits brought this antimalarial medication from Central America to Spain and it spread across Europe. Quinine helped keep Europeans malaria-free and sent colonialism and the slave trade into hyperdrive as Cinchona trees were introduced to Indonesia, Java, the Carribbean, and Africa. In British controlled India, the British East India Company popularized a drink of quinine, carbonated water, sugar, and lime—aka tonic water. Jacob Schweppe created and sold Indian Tonic Water as a “prophylactic against the killer disease.” And so tonic water was born as a disease killing soda water in Colonial India.

Is club soda the same as tonic water?

Nope. Club soda is carbonated water that has minerals added, usually potassium sulfate, sodium chloride, disodium phosphate, or sodium bicarbonate. These give it a slightly salty taste. Tonic water is made with carbonated water, quinine, usually some kind of citrus flavoring, and sugar or some other kind of sweetener to offset the bitterness of the quinine. So what does tonic water taste like? Bitter and a little sweet.

What is tonic water good for?

Tonic water is good for mixing drinks—primarily gin and tonics or other clear spirits and tonic such as white rum or mezcal. These days, there’s not enough quinine in the mix to actually protect against malaria, so don’t try and replace malaria pills with a few gin and tonics on your next safari vacation. That said, some people say it helps them calm their restless leg syndrome. But, really, you should just stick to using it to make delicious G&Ts or sipping it solo on a plane, the only place where it’s acceptable to order straight tonic water.