Lentil and Sausage Soup

½ pound sweet Italian pork sausage, cut into 1/2-inch slices

1 large onion, chopped

1 stalk celery, finely chopped

1 tablespoon chopped garlic

8 cups water

2 (14.5 ounce) cans chicken broth

1 (28 ounce) can diced tomatoes

1 (16 ounce) package dry lentils, rinsed

1 cup shredded carrot

1 tablespoon garlic powder

1 tablespoon chopped fresh parsley

1 tablespoon salt, or to taste

½ teaspoon black pepper

½ teaspoon dried oregano

¼ teaspoon dried thyme

¼ teaspoon dried basil

2 large bay leaves

½ pound ditalini pasta (Optional)