Any person, including municipal corporations, that proposes to establish a water supply consisting of a well, springs, or other source and the necessary pipes, conduits, mains, pumping stations, and other facilities in connection therewith, to serve or to be capable of serving three or more connections shall notify the State Board of Health and shall notify in writing the governing body of the county in which such water system is to be located and shall appear at a regular meeting thereof and notify such governing body in person. In any county having a population of more than 60,000 according to the 1960 or any subsequent census or a county adjoining a city having a population of 200,000 or more according to the 1960 or any subsequent census, no extension of an existing system for the purpose of serving three or more connections shall be made by any person, firm or corporation, other than a municipal corporation, until a plan of such proposed extension, with proof of capacity to serve, has been filed with, and a permit for extension has been obtained from, the sanitation engineer or other county official, if any, designated therefor by the board of supervisors.