Rinse the cranberries then prick them three or four times with a toothpick.
In small saucepan, combine water and sugar over medium heat until sugar is dissolved and simmer for about 5 minutes. Remove from heat and stir in the cranberries.
Cover and allow to cool completely, stirring occasionally – for best results, allow to steep in the fridge for 24 hours or more – then strain the liquid into a clean glass bottle, allowing the cranberries to drain well.
Store in the fridge for up to three months.