Place the tea bags In a large jug or bowl and cover with the boiling water and stir to wet all the tea bags.

Add the sugar and mix well until dissolved.

Cover with a clean tea towel and allow to steep until the mixture has come to room temperature.

Once cool, pour into a large glass or ceramic jar, then add the SCOBY, the cold water, and the kombucha from your previous batch.

Cover with a cloth and allow to sit for 1-3 weeks out of direct sunlight.

You will know when it's ready when it no longer tastes sweet. It should have a sharp, almost vinegary taste.

If any blue or green mould grows, you must discard the entire batch and start again.