A city of the first class or city of the second class may acquire by gift or purchase from the federal government or any agency thereof sewer lines and sewage disposal systems, waterworks, and water distribution systems, whether within or without the corporate limits, and operate and extend the same, even though such system or systems are or may be and continue to be wholly disconnected and separate from any such utility system already belonging to such city, when, in the judgment of the mayor and city council of such a city not having a board of public works or of its board of public works in such a city having such board, it is beneficial to such city to do so. For the purpose of acquiring, maintaining, operating, and extending any such system, any such city may use funds from any sewer, water, or electrical system presently owned and operated by it, without prior appropriation of such funds, and any other funds lawfully available for such purpose.

Rates charged for the use of any system or works acquired under this section shall be reasonable and based on cost properly allocable to the customers of such system.