Cut the lemons or grapefruit in half, squeeze out all the juice with a lemon squeezer, then pour it into a big jug and add the sugar.
Carefully fill a mug of boiling water and pour into the jug with the lemon juice and sugar. Fill the mug again and add to the jug. Using a long-handled wooden spoon, carefully stir until all of the sugar has dissolved.
Add 600ml cold water and mix everything together. Pour into bottles, put the lids on and leave them in the fridge overnight. The lemonade is now ready to drink.
Pour the lemonade into tumblers, add lemon wedges and ice cubes and serve.
If you like the idea of making pink lemonade, just add a good splash of cranberry juice.