Making kombucha at home is straightforward once you understand the basic process: brew sweetened tea, add a live culture, and let it ferment for one to three weeks. In New Zealand, you can source everything you need locally, and the temperate climate works well for brewing most of the year. Here’s how to do it from start to finish.
What You Need to Get Started
The ingredient list is short. You need tea, white sugar, water, a SCOBY (the rubbery disc of bacteria and yeast that drives fermentation), and some starter liquid, which is simply finished kombucha from a previous batch or from the liquid your SCOBY ships in.
For a 4-litre batch, the standard ratio is 200 grams of white sugar and 20 grams of tea leaves (or about 8 tea bags). If you’re starting smaller with just 1 litre, scale down to 50 grams of sugar and 5 grams of tea. Plain white sugar works best. The culture consumes most of it during fermentation, so the finished drink is far less sweet than the tea you start with.
For equipment, you need a wide-mouth glass jar (3 to 5 litres), a breathable cloth cover like a tea towel or muslin, a rubber band to hold it in place, and glass bottles with tight-sealing caps for the second fermentation. Avoid metal vessels and anything with a lead glaze. The brew becomes quite acidic, and acid can leach chemicals from reactive surfaces. Food-grade glass is your safest option. If you use a jar with a plastic spigot, make sure it’s BPA-free.
Where to Source a SCOBY in New Zealand
The easiest route is to get one from a friend who brews. SCOBYs produce a new layer with every batch, so experienced brewers usually have spares. If you don’t know anyone, Symbiota in Papamoa (Bay of Plenty) sells organic live SCOBY cultures and complete starter kits that ship nationwide. They courier live cultures on Mondays and Tuesdays to avoid weekend postal delays. You can also sometimes find SCOBYs through local fermentation groups on Facebook or Trade Me.
Choosing the Right Tea
Use real tea from the Camellia sinensis plant: black, green, white, or oolong. These provide nitrogen, tannins, and polyphenols that the culture needs to stay healthy over repeated batches. The best all-around choice, especially for beginners, is a blend of black and green tea. Black tea promotes strong SCOBY growth and robust fermentation, while green tea contributes a cleaner, crisper flavour. Together they create a reliable, repeatable brew.
White tea makes a lighter, more delicate kombucha. Oolong can produce complex, floral notes. Both work well once you have an established culture. Herbal teas (technically tisanes, not true tea) lack the nutrients the SCOBY depends on. If you ferment only herbals, the culture tends to weaken and thin over time. Stick to Camellia sinensis until your brewing pipeline is stable.
Step by Step: The First Fermentation
Boil your water and steep the tea for 5 to 10 minutes, then remove the leaves or bags. Stir in the sugar until it fully dissolves. Let the sweetened tea cool to room temperature. This is important: adding the SCOBY to hot liquid will damage or kill the culture.
Once the tea is cool, pour it into your glass jar. Add your SCOBY and about half a cup of starter liquid per litre of tea. The starter liquid is acidic and immediately lowers the pH of the brew, creating an environment that’s hostile to unwanted bacteria and mould. Cover the jar with your cloth and secure it with a rubber band. The culture needs airflow but also protection from fruit flies and dust.
Place the jar somewhere warm and out of direct sunlight. The ideal fermentation temperature is 24 to 27°C. In a New Zealand summer, most kitchens sit in this range naturally. During winter, you may need to find a warmer spot, perhaps near a hot water cupboard, on top of the fridge, or with a brewing heat mat underneath. Fermentation slows significantly below 20°C and nearly stalls below 16°C.
Leave the brew for 7 to 14 days. Start tasting around day 5 or 6 using a straw or clean spoon. Early on it will taste like sweet tea. As the days pass, it becomes more tart and vinegary as the culture converts sugar into organic acids. You’re aiming for a balance that tastes good to you, still slightly sweet with a pleasant tang. The pH of finished kombucha typically lands between 2.5 and 3.5. If you have pH strips, check that the brew drops below 4.0 within the first few days. That’s your sign the fermentation is working and the environment is safe.
Second Fermentation: Building Carbonation
The first fermentation produces flat kombucha. For fizz, you need a sealed second fermentation. Harvest your kombucha while it still has a touch of sweetness, even if you prefer a tangier drink. That residual sugar (plus any fruit you add) feeds the culture inside the sealed bottle and produces carbon dioxide, which has nowhere to escape. That’s what creates the carbonation.
Pour the kombucha into glass bottles with airtight caps, leaving a few centimetres of headspace. Add flavouring if you like: a tablespoon or two of fruit juice, a few pieces of fresh fruit, or some dried fruit. Feijoa, apple, ginger, passionfruit, and berry all work beautifully with New Zealand produce. Grape juice, citrus, and pear are also reliable choices. If you’re not adding fruit but still want strong carbonation, a small pinch of sugar or honey per bottle helps.
Seal the bottles and leave them at room temperature for 2 to 4 days. In warmer weather, check after 48 hours by carefully opening one bottle over the sink. If it hisses and fizzes, it’s ready. Move all bottles to the fridge, which slows fermentation and holds the carbonation. Be cautious with this step. Pressure builds inside sealed glass, and bottles can explode if left too long in warm conditions. Burping the bottles (briefly cracking the cap to release pressure) once a day is a good safety habit, especially while you learn your timing.
Keeping Your Brew Healthy
A healthy SCOBY is beige, cream, or light brown. It may look lumpy, bumpy, or uneven. Brown stringy strands hanging from the underside are normal yeast colonies. A new thin layer forming on the surface of each batch is also normal, and that new layer becomes another SCOBY you can use or give away.
Kahm yeast sometimes appears as a thin, white or cream-coloured wrinkled film on the surface. It’s not dangerous, but it can produce off-flavours. It has a smooth, flat texture. Mould, on the other hand, is fuzzy or powdery and often coloured: green, blue, black, or pink. Mould grows on top of the brew, on the SCOBY, or on exposed surfaces above the liquid line. If you see mould, discard the entire batch and the SCOBY. Don’t try to salvage it.
To prevent problems, always use clean equipment, make sure your starter liquid is acidic enough, and keep the fermentation temperature above 20°C. A sluggish, cool brew with a high pH is the most common setup for mould to take hold.
Selling Kombucha in New Zealand
If your home brewing goes well and you start thinking about selling at markets or online, be aware that New Zealand’s Ministry for Primary Industries (MPI) classifies kombucha production under National Programme 3. This means you need to register as a food business and operate under an MPI-approved food safety plan. The requirements cover things like labelling, ingredient traceability, and safe production practices. Check MPI’s guidance on markets and food business registration before you start selling.