What Is Kombucha? A Clear Explanation for Curious Beginners

What kombucha is

At its simplest, kombucha is fermented sweet tea. A brewer steeps black or green tea, dissolves sugar in it, lets it cool, and adds a SCOBY, which stands for symbiotic culture of bacteria and yeast, along with some finished kombucha called starter tea. The mixture ferments at room temperature for about one to two weeks.

The origins of kombucha are murky, with many stories about where and when it began. What is clear is that fermented tea drinks have been made in several parts of the world for a long time. Modern kombucha is usually made with a mixed culture where yeast turns sugar into alcohol and carbon dioxide, and acetic acid bacteria then convert some of that alcohol into acids, which gives the drink its sharp edge.

How kombucha is made

The first fermentation, sometimes called F1, happens in an open-top vessel covered with a tight-weave cloth. Air is important because the acetic acid bacteria need oxygen, and the SCOBY forms a new layer on the surface as the batch matures. After enough time has passed, the brewer pours off most of the kombucha, keeps the SCOBY and some starter tea for the next round, and moves on to flavoring.

The optional second fermentation, or F2, happens in sealed bottles with fruit, juice, ginger or herbs added. The sealed environment traps the carbon dioxide, which makes the drink fizzy. Because of the pressure this builds up, use bottles intended for carbonated drinks and open them carefully. Our article on kombucha first and second ferment explains the stages in more detail.

What kombucha tastes like

Plain kombucha is tart, a bit like a mix of unsweetened iced tea, apple cider and a tiny bit of vinegar, with a light carbonation. Younger batches taste sweeter and gentler, while longer-fermented batches are sharper and more vinegary. The tea you choose affects the flavor too, and black tea gives a rounder, maltier base than green tea.

Many people find that the first sip is surprising, especially if they expect a sweet soda. Commercial brands often add juice or flavorings to soften the sourness. If you are trying it for the first time, begin with a small glass of a lightly flavored version to see whether you enjoy the style before committing to brewing your own.

Is there alcohol in kombucha?

Yes, fermentation produces a small amount of alcohol. Commercial kombucha sold as a non-alcoholic drink in the United States is generally required to stay below a legal limit, and rules around labeling and testing vary. Homemade kombucha is not tested, and the alcohol level depends on sugar, time, temperature and how sealed the bottles are. Extended second fermentations in sealed bottles tend to increase it.

If you avoid alcohol for religious, medical or personal reasons, or you are pregnant, you should take this into account and speak with a doctor if unsure. Children are usually advised not to drink homemade kombucha, and anyone with a weakened immune system should ask a medical professional before trying unpasteurized fermented drinks.

Safety basics for homemade kombucha

Cleanliness and acidity are the main safeguards. Wash all equipment with hot soapy water and rinse thoroughly, and use enough starter tea so the batch starts out acidic. A pH strip or meter can confirm that a new batch drops to a safe, acidic range early on. Our pH meter guide and brewing thermometer strip guide cover tools that make this easier.

Avoid fermenting in vessels with lead-containing glazes, cracked ceramics or reactive metals such as copper and unlined aluminum, since the acidic liquid can pull materials out. Glass, food-grade stainless steel and food-safe plastic are common choices. Fuzzy, dry, raised spots on the SCOBY or liquid are mold, and the entire batch should be discarded.

See pH meters for fermenting →

Getting started with a kit or a starter

A live SCOBY and starter tea are the essential ingredients, and many beginners get them from a friend or from a starter kit. A kit usually bundles a SCOBY, a vessel and tea or sugar, though contents differ between products. Our SCOBY starter kit and kombucha brewing kit guides compare what is included so you can choose based on your preferences.

Whatever you start with, plan on a first batch that is an experiment. Keep the vessel in a stable spot away from direct sun, taste a small sample after about a week, and look for a balance of sweet and tart that you enjoy. Our beginner article on how to make kombucha at home gives a complete step-by-step recipe to follow.

Compare kombucha brewing kits →

Common questions beginners ask

People often ask whether the stringy brown bits in a batch are a problem. Brown strands hanging from the SCOBY or floating in the liquid are usually yeast, and they are a normal part of the culture. The SCOBY itself can look lumpy, pale, bumpy or even sink or float, and none of that necessarily signals trouble. The warning signs are fuzzy mold on top and a rotten smell, not an odd shape.

Another frequent question is how much to drink. There is no single answer, and the evidence on health benefits is limited, so it is sensible to start with a small glass and see how you feel. Because kombucha is acidic and contains caffeine from the tea, some people find that large amounts upset their stomach. Treat it as a flavorful drink to enjoy occasionally, not as a medicine.