S.C. Code § 5-31-890
All municipalities in this State owning, controlling, leasing or planning to construct a system of sewage disposal with or without outfalls, rights of way, easements and appurtenances thereto, may, through proper officials, commissioners of public works, sewer commissions or any of them or like bodies, enter into contracts and agreements with persons or political subdivisions outside the corporate limits of such municipalities, whether contiguous thereto or not, for the construction, maintenance, operation, improvement, leasing, controlling or furnishing the use, benefits and facilities thereof upon such terms and at such rates and charges as may be fixed by the contract or agreement between the parties when, in the judgment of the proper officials, commissioners of public works, sewer commissions, or any of them or like bodies, as the case may be, it is for the best interest of the city, town or municipality so to do. But no such contract or agreement shall be for a period exceeding thirty years from the effective date thereof.
Nothing herein contained shall be construed as abrogating, limiting or qualifying any contracts or agreements of the nature set forth herein which may have heretofore been entered into and under which the parties thereto are operating.
S.C. Code § 5-31-890