The board shall establish a department in county government for the purpose of establishing, operating and maintaining the system or systems of sewerage and/or water. In the department, the board shall establish and provide for the operation and maintenance of a personnel merit system for the employment, classification, promotion, demotion, suspension, transfer, layoff and discharge of its appointive officers and employees, solely on the basis of merit and fitness, without regard to political influence or affiliation. Such merit system shall not apply to the chief administrative officer of the department and, if the sewer and/or water utility is a division of a department having other functions, the chief administrative officer of such utility.