In a Dutch oven or large saucepan, simmer rhubarb and water until rhubarb is soft, about 10 minutes. Cool; strain through several layers of cheesecloth. Measure 4 cups juice and return to Dutch oven with the sugar. Heat until sugar is dissolved. Chill.
Refrigerate or freeze any remaining rhubarb juice for another batch. Combine orange and lemon juices and rhubarb mixture. Refrigerate until ready to serve. Just before serving, stir in ginger ale and, if desired, strawberries. Serve in chilled glass over ice.