Preheat your slow cooker. To the slow cooker, add the fully-cooked pork sausage, cream cheese, sour cream, green chilies, water, cayenne pepper, garlic powder, and onion powder. Cook over low heat for 1 hour. Stir the dip and give it a taste. Adjust seasoning by adding salt and black pepper if necessary. Add the cheddar cheese and stir. Cook the dip for an additional 1-2 hours until melty and warm. Keep the dip warm until you are ready to serve.