In a medium skillet, cook the ground beef until browned over medium heat. Drain, and set aside.
Place the ground beef, onion, chili beans, kidney beans, corn, tomato sauce, water, diced tomatoes, green chile peppers and taco seasoning mix in a slow cooker. Mix to blend, and cook on Low setting for 8 hours. (or 4 to 5 hours on high)
Serve with sour cream, cheddar cheese, and or tortilla chips, if desired