The city reserves the right at any time to shut off the water in its mains for the purpose of making extensions or repairs, or for other purposes, and all persons having boilers within their premises not supplied with tanks or cisterns, but depending upon the pipes of the city to keep them supplied, are cautioned against danger of collapse or other damage. The city shall not be liable for damage which may result from an interruption in service from any cause beyond the control of the water department. (Prior code § 23-25)