Preheat oven to 325º F.
Trim all fat from roast. Rinse well with cold water. Place roast in a large covered casserole dish. Combine soup mix, cream of mushroom soup, water and Worcershire sauce; pour over roast. Cover and bake at 325º F for 2 hours. Add onions and carrots and bake, covered for an additional hour. Add potatoes and bake, covered for an additional hour. Sprinkle mushrooms on top of roast, and bake for 20 more minutes. Serves 4.