Tarro, té, azúcar

Kombucha needs almost nothing. What it needs, it needs to be right.

The jar

3–5 litres, wide-mouthed, glass or food-grade ceramic. Never metal for long contact — the acid will pit it — and never decorative glazed ceramic, which can leach lead. Cover with tight-woven cloth and a band, not a lid: F1 needs air and needs to keep fruit flies out.

The bottles

Swing-top (Grolsch-style) glass, 250–500 ml. They hold pressure, and reused ones are better than new ones in every respect except appearance. Bottle reuse is the single largest lever on kombucha's footprint: glass is heavy, and the impact of a bottle is almost entirely in making and shipping it, not in the drink. A swing-top used fifty times is effectively free. Check the rubber gasket every few months; replace the gasket, not the bottle.

The tea

Plain black or green tea, loose leaf. Avoid oils and flavourings (Earl Grey's bergamot suppresses the culture over repeated batches). Loose leaf also sidesteps the plastic mesh in most pyramid bags and the polypropylene sealing many paper bags.

Where the tea comes from is a live ethical question — plantation labour conditions in Assam and Sri Lanka are documented and uneven. A named estate or a small importer who publishes purchasing terms is worth the extra euro or two.

The sugar

Plain white granulated. Not honey (antibacterial, and raw honey introduces competing organisms), not stevia, not coconut sugar for a first batch. The culture eats the sugar; almost none of it remains in a well-fermented brew.

Cane or beet is the real choice. Beet sugar in Europe is grown and refined regionally, so transport is short, but it is intensive on soil and water. Cane sugar carries a longer supply chain and a much heavier labour history; Fairtrade or a named cooperative is the meaningful signal, not the word "raw". Neither answer is clean — but the honest version is that you are using roughly 60 g per litre, and buying the better-documented bag costs cents per batch.

Water

Chlorine inhibits the culture. Boil, or leave tap water uncovered overnight, or filter. Chloramine (used in some Dutch supply areas) does not off-gas — filter it.

What to skip

Heating mats, pH meters, brewing kits with branded sachets, and the second SCOBY hotel you will not maintain.