Mix zucchini, water, chicken broth, onion, bacon, garlic, salt, pepper, and basil together in a large pot; bring to a boil and cook until the zucchini is tender, about 30 minutes.
Pour soup into a blender no more than half full. Cover and hold lid down; pulse a few times before leaving on to blend. Puree in batches until smooth. Top with Parmesan cheese to serve.