Cooking pork sausages can be done in different ways and each method has different timeframe for cooking. Boiling it is just one way which may take around 20 minutes depending on the size and thickness of your sausage, 20 minutes would be enough for an average size. You may opt to grill your pork sausages, which is recommended because it reduces the fats but at the same retains the flavor, unlike boiling them in water. For grilling method, it takes up to 40 minutes to make sure that the sausage is cooked through. You can also cook them in a pan with a little bit of oil which takes 30 minutes, same cooking time applies if you bake sausages. There are some who prefer to boil them first for 10 minutes then grill or cook them in a pan for another 10-15 minutes. For safety and for more accurate cooking method, you may use a kitchen or meat thermometer. If your pork sausage reached 165 degrees in the center then it is already cooked.