In a deep skillet or dutch oven, stir the milk, water, and salt together over medium high heat. Stir in the uncooked macaroni and bring to a boil. Reduce to a simmer and cook, stirring very frequently, for about 8 minutes or until the pasta is tender and most of the liquid has been absorbed. Turn off the heat and stir in the cheese. Stir until melted. Serve immediately.