Odds are you’ve tried (or at least heard of) kefir, the creamy fermented drink with a texture like drinkable yogurt. Although it’s often just referred to with one name, the dairy-based drink is technically milk kefir. Turns out, other liquids can be fermented into kefir, including plain old water. Similar to its milk-based counterpart, water kefir is not difficult to make, but it does take a decent amount of time and patience. The drink begins with water kefir “grains” known as tibicos, a culture of bacteria and yeasts that acts as the fermentation starter. When mixed with water and sugar, the water kefir grains feed off the sugar to produce carbon dioxide gas, also known as fizziness. Finished water kefir is a sweet, slightly cloudy drink that can be flavored further with fruit or sipped on as-is.
First things first: To make water kefir, you will need to buy water kefir grains, which are luckily not tricky to find (thanks, internet!). Next, activate your water kefir grains as directed on the package. Mix ¼ cup granulated cane sugar with 1 cup warm non chlorinated, non fluoridated water (spring or filtered water works) in a 2 quart jar until the sugar dissolves. After the sugar dissolves, mix in 4 cups room temperature water. Use a thermometer to ensure the water is at room temperature (about 70ºF, give or take 5 degrees, is a good temperature to look for), then mix in a scant ¼ cup of activated water kefir grains.
Loosely cover the jar with a lid or a dish towel or coffee filter and rubber band. Place the jar in a warm place (a kitchen counter is typically the best choice) and let the mixture hang out to ferment for 24-36 hours.
Strain out the water kefir grains from the water kefir using a fine mesh sieve made from plastic or stainless steel (other metals like aluminum can mess with the kefir grains.) To have a constant supply of water kefir, repeat the first two steps of this process with the remaining grains—if all goes well, the grains will continue to multiply for many batches of water kefir.
Strained water kefir can be drank as-is, flavored, or given a secondary ferment for extra fizziness. For flavoring, stir in ¼ cup citrus or berry juice. For the secondary ferment, transfer flavored or unflavored water kefir into flip-top heavy-duty glass bottles, leaving about 1 inch of space unfilled. Cap the bottles and let sit at room temperature for 18-72 hours. If the space where the bottles are kept warm, you’ll need to “burp” the bottle every 18 hours. Burping a bottle is a giggle-inducing term that will actually save you a lot of cleanup: Holding your finger on the top of the jar, flick off the seal and let the water kefir bubble to the surface. Just before it starts to burst out of the bottle, reseal the cap. Un-burped, water kefir can get so fizzy it will spurt out of the bottle as bubbles, leaving you barely anything left to drink.
Once you’ve fermented water kefir to your desired fizziness, place bottles in the fridge to chill for at least 6 hours and up to 3 days, then open over the sink just in case it fizzes up.