In this chapter:
(1) "Combined system" means any combination of one or more of the following:
(A) an electric system;
(B) a water system;
(C) a sewer system;
(D) a solid waste disposal system;
(E) a drainage utility system; and
(F) a natural gas system.
(2) "Public security" has the meaning assigned by Section 1201.002.
(3) "Utility system" means an electric, water, sewer, solid waste disposal, drainage utility, or natural gas system. The term includes one or more combined systems.