S.C. Code Ann. § 6-25-60
(A) The management and control of a joint system is vested in a commission that may consist of no fewer than five members and no more than eleven members. The governing body of each voting member of a joint system shall appoint a commissioner, pursuant to Section 6-25-50(A), to serve as a commissioner of the joint system. A commissioner has one vote and may have additional votes as a majority of the members of the joint system determines. A commissioner serves at the pleasure of the governing body by which he was appointed. A commissioner, before entering upon his duties, shall take and subscribe to an oath before a person authorized by law to administer oaths to execute the duties of his office faithfully and impartially, and a record of each oath must be filed with the governing body of the appointing authority.
Notwithstanding the provisions of this subsection requiring the commission managing a joint system to have no fewer than five members and no more than eleven members, a joint system in existence on this section's effective date and having fewer than five members or more than eleven members on this section's effective date may continue to maintain the number of members serving on the section's effective date and may add additional members as its commissioners determine.