Neb. Rev. Stat. §§ 18-405
Upon the completion of an extension or enlargement of any water or gas main or other utility service in a water main district, gas main district, sanitary sewer district, storm water disposal district, or other public utility district created pursuant to section 18-401, the actual cost of such extension or enlargement shall be duly certified to the city council, village board of trustees, or board of directors of a metropolitan utilities district when done by contract, but when done by utilizing the equipment and employees of any such city, village, or metropolitan utilities district, the average cost, based upon the average cost per foot to such city, village, or metropolitan utilities district in the previous calendar year, of installing water or gas distribution mains, as the case may be, shall be thus certified. Such city council, village board of trustees, or board of directors shall assess, to the extent of special benefits, the cost, not exceeding the actual cost or average cost, as the case may be, of installing such water main, gas main, or other utility service, upon all real estate in such district, in proportion to the frontage of the real estate upon the main or utility service. The cost of any such extension or enlargement in excess of the actual or average cost of installing the water main, gas main, or other utility service authorized to be assessed and levied against the real estate in such district shall be paid out of the water fund, gas fund, or other utility fund of such city, village, or metropolitan utilities district, if there is such a fund, and if such city or village has no water fund, gas fund, or other utility fund, then the costs shall be paid out of the general fund. No real estate in any city, village, or metropolitan utilities district shall be subject to more than one special tax assessment for the same extension or enlargement of water mains, gas mains, or other utility service.
Neb. Rev. Stat. §§ 18-405