S.C. Code § 6-17-40
For the purpose of this chapter a governing body may by resolution combine two or more projects, works, undertakings or systems into a combined system or enterprise. A governing body may also combine into one system or enterprise any existing project, work, undertaking or system with any proposed project, work, undertaking or system which such governing body shall have deemed to be related and the initial construction of the proposed project, work, undertaking or system shall, for all purposes of this chapter, be considered an improvement, extension or betterment of the existing enterprise. Governing bodies are specifically empowered to combine into one enterprise an existing waterworks system with a proposed sewer system and, for the purpose of this chapter, the initial construction of the sewer system shall be deemed an improvement, extension or betterment of the existing waterworks system.
S.C. Code § 6-17-40