Sec. 258. (a) "Wastewater treatment plant", for purposes of IC 13-18-11 and IC 13-20-17.5, and environmental management laws, means the system of treatment works, regulatory devices, equipment, and other facilities and appurtenances installed to treat sewage, industrial wastes, and other wastes delivered by a system of sewers and other related facilities, whether owned or operated by the state, a municipality, or a person, firm, or corporation. The term does not include septic tank disposal systems.
(b) "Wastewater treatment plant", for purposes of IC 13-18-26, means the system of treatment works, regulatory devices, equipment, and other facilities and appurtenances installed to treat sewage and other wastes that are delivered by a system of sewers and other related facilities, regardless of whether the system of treatment works, regulatory devices, equipment, and other facilities and appurtenances is owned or operated by the state, a municipality, a person, a firm, or a corporation. The term does not include a system that is installed by a company or industry and used to treat industrial wastes prior to discharge of the wastewater in accordance with a permit issued by the department or another entity to which permitting authority has been delegated.