Any water district board may contract with any other water utility, as defined by Kan. Stat. Ann. § 19-3501, and amendments thereto, or any school district, state department, state institution, board of county commissioners of any county, township, municipality or political subdivision of the state of Kansas, for the purpose of supplying water. Such other water utility, school district, state department, state institution, county commissioners, township boards, municipalities and political subdivisions of the state are hereby authorized to contract and pay reasonable rates and charges for such water and for additions for enlargement of the water supply and distribution system which are attributable to the demand for water by such entities located outside the district. Any such contract may extend for a period of years not longer than the period for which revenue bonds are issued.