Whenever, under any street improvement act under which public work or improvements may be installed or constructed and the costs and expenses assessed in whole or in part against the lands or property benefited, there have been installed or constructed within any city or within the unincorporated territory of any county any wells, pumps, dams, reservoirs, storage tanks, channels, tunnels, conduits, pipes, hydrants, meters, or other appurtenances for supplying or distributing a domestic water supply, or all or any combinations thereof, and whenever there have been installed or constructed within any city or within the unincorporated territory of any county any mains, services, pipes, fittings, valves, regulators, governors, meters, drips, drains, tanks, ditches, tunnels, conduits, channels, or other appurtenances for supplying or distributing a domestic or industrial gas supply, or all or any combinations thereof, and no provision has been made for the maintenance, operation, and use of the work or improvement constructed, and the city owns no plant or system which can conveniently furnish water or gas, or the county owns no plant or system which can conveniently furnish the water or gas, the legislative body of the city or county, as the case may be, may grant permission to furnish water or gas therefor to any district, public corporation, mutual company, public utility company, private company, or individual.