Tennessee Code Title 68. Health, Safety and Environmental Protection § 68-221-907

The board shall classify all water treatment plants, wastewater treatment plants, water distribution systems, and wastewater collection systems with due regard to the size, type, physical conditions affecting such treatment plants, collection systems and distributions systems, and according to the skill, knowledge and experience that the operator must have to supervise successfully the operation of the plant or system, so as to protect the public health.