Make the sugar water

• Pour the water into a clean glass jar.
• Add the sugar and stir until it is completely dissolved.

First fermentation

• Add the active water kefir grains to the sweet water.
• Stir in the lemon juice.
• Cover the jar loosely (cloth or lid ajar) and let it ferment at room temperature until lightly fizzy and slightly tart.

Strain the grains

• Strain the liquid through a plastic sieve to remove the kefir grains.
• Set the grains aside to reuse for your next batch.

Flavour with cola

• Stir the cola syrup into the fermented water kefir.
• Pour into pressure-safe bottles, leaving a little headspace.

Second fermentation

• Seal the bottles and leave them at room temperature to build carbonation.

Chill and serve

• Refrigerate the bottles until well chilled.
• Open carefully and serve cold as a probiotic cola soda.