S.C. Code § 5-31-50
All cities and towns of this State may grant to persons the exclusive franchise of furnishing water or waste disposal service to such cities and towns and the inhabitants thereof for a period not exceeding forty years. No such franchise shall be valid unless it shall first receive the vote of two thirds of the governing body of the city or town granting it and be subsequently confirmed by a vote of a majority of the qualified electors of such city or town, voting at an election to be called specially for the purpose. Any ordinance or resolution granting such a franchise shall prescribe a method for determining rates for furnishing water, both for public and private consumption, and for waste disposal service, and make provision for periodic renewal of such franchises. No such franchise shall exceed a period of forty years from the initial delivery of water or the commencement of waste disposal services or affect any existing contractual rights.
S.C. Code § 5-31-50