When it is necessary to conduct the sewage of a municipality beyond the municipal limits or to acquire a supply of water beyond such limits and to construct mains or aqueducts to conduct such water to the municipal limits, the governing body, by grant, purchase, or condemnation proceedings, may acquire private property over which to construct the sewer, or upon and over which to establish facilities for obtaining and storing such water supply and aqueducts or mains for conducting the same to the corporate limits. Public property may likewise be acquired for such purposes by grant or purchase from the government or public corporation owning the same. The cost of acquiring such property and of building such sewer or other facilities upon or over the property may be included in the cost of construction or acquisition of a municipal waterworks or sewerage system and in the special assessments levied therefor, or the entirety of such a project may be completed as an improvement to an existing waterworks or sewage     system and special assessments may be levied therefor in accordance with the provisions of this title.