Place the blackcurrants, sugar and water in a medium saucepan. Heat gently, stirring occasionally, until the sugar has dissolved and the fruit begins to release its juice. Bring the mixture to a gentle simmer and cook for approximately five minutes. Stir occasionally and lightly crush some of the berries with the back of a wooden spoon as they soften.The fruit is ready when most of the blackcurrants have burst and the mixture looks juicy and syrupy.