Large floods from stormwater runoff may occasionally occur which exceed the prudent design capacity of the drainage facilities constructed or maintained by funds made available under this article. This article does not imply that the real property liable for the drainage basin development and monthly usage fees established in this article will always be free from stormwater flooding or flood damage nor shall this article create any liability on the part of or cause of action against the city or any officer, agent or employee thereof for any flood damage that may result from storms or the runoff thereof or purport to reduce the necessity for obtaining flood insurance. (Code 1979, § 17-27)