Mo. Rev. Stat. § 256.611: Application, qualifications.

The division shall issue a permit as a well installation contractor, heat pump installation contractor, monitoring well contractor or pump installation contractor to any person properly making application therefor, who is not less than eighteen years of age, has a knowledge of rules and regulations adopted under sections 256.600 to 256.640, and has passed the appropriate examination and has supplied proof of adequate experience as specified by rule and regulation.