Bring the water to a boil. Add the tea to the water - I use green tea.
Turn off the heat, put the lid on and let it steep for 15 minutes. Pour off the tea leaves and stir in the sugar until dissolved.
Let the mixture cool to room temperature and then pour it into a fermentation jar. I use a large glass jar with a screw cap.
When the mix is cool, add the kombucha mushroom to the tea. Pour the finished kombucha into it.
Cover the fermentation vessel with a kitchen towel. Fasten the cloth with a rubber ring. Now the mushroom can breathe and is protected from dust, dirt and fruit flies.
Place the jar in a warm place and do not move it for the next few days.
After 8 days you can taste it for the first time and see if it is sour enough for you. If yes: Pour the drink through a sieve, fill it into bottles and put it in the refrigerator.