The City shall not be liable for any damage resulting from bursting of any sewer main, service pipe or valve, or by discontinuing the operation of its sewer collection, treatment and disposal facilities for repairs, extensions or connections or from the accidental failure of the sewage collection, treatment and disposal facilities from any cause whatsoever. In cases of emergency the Sanitary Board shall have the right to restrict the use of its sewage collection, treatment and disposal facilities in any reasonable manner for the protection of the City and its sewage system. (1978 Code Sec. 23-18.)