Grapefruit and ginger cordial

This cordial is popular with children and makes a delicious mixer for adult drinks.
(yields about 600 ml):
Prep/cooking time: about 20 min. plus chilling..

250 ml pink or yellow grapefruit juice (2-3 fruits)
250 g white sugar
250 ml water
Fresh ginger to taste (I used 2-3 cm)

Juice the grapefruits. Peel the ginger and slice it thinly.
Pour the grapefruit juice into a small saucepan, add the sugar and water as well as the sliced ginger. Bring to a boil and allow to simmer until sugar has completely dissolved.
Remove from heat and let stand for 10 to 15 minutes. Pour through a fine mesh sieve into a sterilised bottle and refrigerate the strained syrup until thoroughly chilled. Seal the bottle. Store in the refrigerator.
To cut the sweetness, dilute with water or soda water and ice cubes.