Add the vegetable stock, water, diced tomatoes, tomato paste, carrots, celery, sweet onion, garlic, kidney beans, cannellini beans, Italian seasoning, bay leaves, salt, black pepper, and Parmesan rind to the slow cooker. Stir everything together.
4 cups Vegetable stock, 2 cups Water, 1 (28 ounce) can Diced tomatoes, 2 tbsp Tomato paste, 1 cup Diced carrots, 1 cup Diced celery, 1 cup Sweet onion, 4 cloves Garlic, 1 Parmesan rind, 1 (15 ounce) can Dark red kidney beans, 1 (15 ounce) can Cannellini beans., 1 tbsp Italian seasoning, 2 Bay leaves, 1/2 tsp Kosher salt, 1/2 tsp Ground black pepper