Add the sugar and water into a saucepan on medium heat and bring to a gentle boil, stirring a couple of times.
250 ml water, 500 g white sugar
Reduce the heat to very low and simmer for 5 minutes. Stir in the red food colour while it's simmering, so the red paste has time to dissolve, if necessary. You want a deep red colour, so it'll dilute to pink.
Leave to cool for 10 minutes, then stir in the rose water.
2 Tbsp of rose water
Pour into a sterilised bottle or jar and can be stored at room temperature for about a month although I prefer to keep mine in the fridge and it has gone for as long as 2 months.
To serve, dilute like a cordial, at a ratio of 1 part syrup to 4 parts water or 1:3, depending on how sweet you like your drinks.