Drain the pot, add butter and set over low heat. Once melted, add flour, salt and pepper. Cook butter and flour mixture for 2 minutes, or until it is golden brown and smells nutty. Increase the heat to high, add the milk, water and pasta, and bring to a boil, then reduce heat to a simmer. Cook, stirring frequently, for 15 minutes, or until the pasta is tender and the milk has reduced to a thick and creamy sauce.