Makes 1.5 litres
350ml lemon juice
220g (1 cup) caster sugar
1.25 litres soda water
2 lemons, thinly sliced
2 cups ice, plus more for serving
1. Add the lemon juice and sugar to a large jug or jar. Pour in about half the soda water, and stir until the sugar dissolves.
2. Pour in the remaining soda water, then add the lemon slices and ice. Serve in tall glasses, adding extra ice if desired.