Add all the ingredients, except the water, to a large soup pot or slow cooker. Add enough water to fill the pot (expect to use about 8 cups). Cover and bring to a slow and low simmer for 1 to 2 hours if just using vegetables. If using bones, simmer for 2 to 6 hours (up to 24 hours in a slow cooker on low). The soup will get richer and more flavourful the longer you let it simmer.