Bring the water, sugar, and grated ginger to a boil in a pot.
Simmer for about 5–10 minutes to infuse the ginger flavour.
Remove from heat and stir in the lemon juice and cream of tartar.
Allow the mixture to cool until lukewarm.
Add the yeast and stir gently.
Pour into a clean plastic bottle or glass bottle (leave some space at the top).
Leave at room temperature for 24–48 hours to ferment and develop fizz.
Once fizzy, refrigerate to stop fermentation.