In a large pot, combine the water, rhubarb, and lemon zest. Allow it to come to a boil. Once boiling, reduce the heat and continue to simmer for approximately 15 minutes. At this point, add the strawberries and cook for another 2 to 3 minutes.
3 ½ cups water, 1 lb rhubarb, zest of 2 lemons, 3 cups fresh strawberries