Heat the sugar and the water in a large saucepan until the sugar completely dissolves
Add the citric and tartaric acids and stir them to dissolve as well.
Add the citrus juice and the zest to the sugar syrup.Leave to infuse for 1/2hr then strain into a jug
Ensure that the glass bottles are hot when you add the hot fruit syrup, as the hot syrup will crack them otherwise. [Wear washing gloves as this will protect your hands and wrists from the hot syrup]
To serve: dilute with 2/3 sparkling water or soda water or perhaps a clear spirit for the grown-ups like Gin or Vodka….whatever takes your fancy!