This Good Question comes in to us from Amber, just in time for the beginning of tall, cool drink season:
At the risk of sounding uneducated about bar staples, I'm posing my question to you Kitchn foodies. I'm wondering...What's the difference between tonic water, mineral water, seltzer, carbonated water, and club soda? They all seem like fizzy water alternatives, and they may be identical. But could I, say, make one of those exquisitely refreshing-looking gin and tonics with the mineral water that I keep stashed in the fridge?
Amber, all of these types of fizzy water are indeed quite similar. All of these types, that is, except tonic water. Although its name might lead you to think otherwise, tonic water doesn't taste very "watery" at all. Rather, it has a very strong and distinctively bitter flavor that you'll notice on the very first sip. This bitterness comes from a compound called quinine, which is added to the water base along with some sugar to make a carbonated beverage that happens to be a heavenly match for the juniper-y taste of gin (more on this here). So, to make a long story short, when mixing yourself a gin and tonic, nothing but tonic water will do.
As for the others waters you mentioned...
Soda water, seltzer, carbonated water, club soda, sparkling water, mineral water. Names for fizzy water do tend to get tossed around loosely, and almost interchangeably. But there are some important distinctions to keep in mind:
"Carbonated water" is a good umbrella term for all the fizzy waters you mentioned. Club soda, seltzer, and mineral water all get their effervescence from dissolved carbon dioxide.
Mineral water is water containing dissolved, naturally-occurring minerals (and sometimes fizz-making carbon dioxide), that is drawn and bottled directly from an underground natural source. These dissolved minerals give the water a subtle flavor, and, some believe, impart important health benefits. There are hundreds of different regional waters available on the international market, each with its own distinct mineral profile. Some of the most famous are Perrier and San Pellegrino (which are both naturally carbonated), and Volvic (which is naturally flat). (Note: in order to be labeled "mineral water," as opposed to "spring water," the water must contain at least 250 parts per million (ppm) naturally occurring dissolved mineral solids.)
Uses: Because of its higher price and, well, mineral-y flavor, mineral water is not usually used to make mixed drinks. It is best enjoyed on its own or with a slice of lemon or lime.
Seltzer is plain, unflavored water that has been artificially carbonated. Named after the German town of Niederselters, which is known for its natural springs, seltzer was first marketed in the USA as an affordable domestic alternative to pricey imported mineral waters. Because of the explosive pressure created by the carbonation, seltzer was originally sold in thick glass bottles fitted with metal siphon tops. (If you've seen any old slapstick comedies, you've probably seen these iconic spray bottles in action!) Since then, siphon bottles have mostly gone by the wayside - although there does seem to be a bit of a recent revival. Modern-day "seltzer" is now commonly sold in ordinary plastic soda bottles.
Although it's used almost interchangeably with seltzer, club soda is a slightly different beast. While seltzer is plain carbonated water and nothing but, club soda usually has a few mineral-y ingredients mixed in for added flavor (see the "carbonated water, potassium bicarbonate, potassium sulfate" listed on the label directly above vs. the simple "carbonated water" pictured above that on the seltzer bottle). I tasted a sample of each side by side (both manufactured by the same company, Schweppes) and found that there was indeed a subtle difference. The (sodium-free) club soda I sampled had a very faint baking soda taste that gave it a little extra zip. I found it slightly more refreshing, but the difference was very, very small.
Uses: Both seltzer and club soda are suitable mixers for highball drinks.
Related: How to Make Soda Water at Home
(Images: Nora Maynard)