Combine fruit, sugar and water in a large pot. Bring to a boil over medium heat and stir until the sugar dissolves. Reduce the heat to a simmer and cook until the fruit softens and starts to release it's juices, about 10 minutes.
Taste and adjust for sweetness. Allow to cool to room temperature, then refrigerate for at least 4 hours and preferably overnight. *See note
Ladle cold Kompot into tall glasses along with some of the fruit. Top with a splash of club soda and a scoop of vanilla ice cream, if using. Serve with a long spoon.
Notes
*I usually put the whole pot in the refrigerator but you can also store the Kompot in a Tupperware container. It will stay fresh for several days when refrigerated.