Ala. Code § 22-25-2

The director shall classify all water treatment plants, water distribution systems, wastewater treatment plants, and public wastewater collection systems affecting the public welfare with regard to the size, type, character of water and wastewater to be treated, and other physical conditions affecting the treatment plants and distribution systems; and according to the skill, knowledge, and experience that an operator must have to supervise the operation of the facilities to protect the public health and prevent pollution.