First, find a sealable sterilised clip-top bottle for the syrup.
Bring the water to a boil in a pan and then turn off the flame.
Add the sugar and stir until it dissolves.
Put the elderflowers in the pan, cover and let it soak for 20-30 minutes.
Pour the elderflower juice through a sieve to sift out the flowers.
Pour the syrup into the bottle, let it cool and then keep the bottle in the fridge.