In a glass jar, combine 1 cup of water, 2 tablespoons of grated ginger, and 2 tablespoons of sugar. Stir well to dissolve the sugar.

Cover the jar with a cloth and secure it with a rubber band. Let it sit at room temperature for 3-5 days, stirring daily until bubbly and active.

In a bowl, mix 4 cups of water with 1 cup of sugar until dissolved.

Add 1 cup of the prepared ginger bug starter and 1 tablespoon of lemon juice (if using). Stir to combine.

Pour the mixture into clean bottles, leaving some space at the top. Seal the bottles tightly.

Let the bottles sit at room temperature for 2-3 days to ferment. Check daily for carbonation.

Once carbonated, refrigerate the bottles to stop fermentation. Serve chilled.