Ariz. Rev. Stat. § 49-361
The department shall adopt and enforce rules to classify sewage collection systems and treatment plants and to certify operating personnel according to the skill, knowledge and experience necessary within the classification. The rules shall provide that operating personnel may be certified on the basis of training and supervision at the place of employment. The department may assess and collect reasonable certification fees to reimburse the cost of certification services, and the fees shall be deposited, pursuant to sections 35-146 and 35-147, in the water quality fee fund established by section 49-210. The rules apply to all sewage treatment plants that receive and treat wastes from common collection sewers and industrial plants but do not apply to septic tanks, to devices that serve a single home or to industrial treatment devices that are used to perform or allow recycling or impounding wastes within the boundaries of the industry's property.
A.R.S. § 49-361