Boil filtered water. Make a cup of tea. Let it cool.

Pour matured kombucha into a sterilised glass. If you have SCOBY, put it inside too. Pour sugar into glass.

When the tea is completely cool, pour into the glass bottle. Cover with a plastic cap or wrap with good paper towel.

Place the bottle in warm room and taste the kombucha after 5 days. If still got 'tea' taste, leave it for few more days as it is not fully fermented yet.