Add the beef to the slow cooker. Sprinkle the ranch seasoning and brown gravy powder over the beef. Add the cream of mushroom soup and stir to combine.
Pour in the water and stir once more.
Cover the slow cooker and cook on LOW for 6-8 hours or HIGH for 4-6 hours.
When there is 1 hour left in the cooking time, add in the noodles and stir them into the sauce as all the noodles get wet.
Cover and cook for the last hour until the noodles are cooked and tender. Portion into bowls and serve warm.
Notes
You can buy pre-cut stew beef at most grocery stores. If you prefer, you can buy a 2-pound chuck roast instead. Trim the roast and cut it into 1-inch cubes before proceeding with the recipe.