(12 fluid ounce) cans or bottles beer
Place bratwurst, beer, onion, and ketchup in a slow cooker. Pour water over mixture until everything is covered. Set slow cooker to HIGH and cook for 4 hours. 2Preheat an outdoor grill for high heat and lightly oil grate. 3Grill bratwurst on preheated grill until they are browned, about 5 minutes.