Combine water and rice in a saucepan, and bring to a boil. Reduce heat, cover, and simmer for 20 minutes.
Preheat oven to 350 degrees F (175 degrees C). Lightly grease a 9x13 inch baking dish.
In a large bowl, mix the soup, sour cream, poppy seeds, and dill. Stir in the chicken and cooked rice. Spread the mixture into the prepared baking dish. In a small bowl, mix the cracker crumbs and butter; sprinkle over the casserole.
Bake in the preheated oven for 30 minutes. Let cool for 5 minutes before serving.