The governing body of any county notified of the proposed establishment of a water system or of the extension of any existing water system under the second paragraph of § 15.2-2149 may disapprove the same, if it finds that such water system does not have an adequate source of supply, or that the system is not capable of serving the proposed number of connections by reason of inadequate pipes, mains, conduits, pumping stations, or otherwise. If, at the expiration of seventy days from the date on which the applicant appeared before the governing body, such governing body has not disapproved the application, the applicant may proceed with the construction and installation of such water system, provided he first gives notice to the chairman of the governing body by registered mail of his intention to proceed.