Any city may establish an administrative agency known as the board of public utilities of such city, to be elected in the manner hereinafter provided. The board shall manage, operate, maintain and control the daily operation of the water plant and electric-light plant of such city, and shall make all such rules and regulations as are necessary for the safe, economical and efficient operation and management of such water plants and electric-light plants. The board may also improve, extend or enlarge the water plants and electric-light plants as hereinafter provided, and furnish a supply of water, light, heat and power for domestic, industrial and municipal purposes.