(a) An individual who performs process control duties in production or distribution of drinking water for a transient non-community water system as defined in §290.38 of this title (relating to Definitions), is exempt from the licensing requirements of this subchapter, if the source water for the water system is purchased treated water or groundwater that is not under the direct influence of surface water.(b) An operator-in-training under the direct supervision of a licensed public water system operator is exempt from the licensing requirements of this subchapter.(c) A military operator-in-training under the direct supervision of a licensed public water system operator is exempt from the licensing requirements of this subchapter for the purpose of collecting microbiological samples or determining disinfection residuals at military facilities' water distribution systems. The military operator-in-training is not exempt from the licensing requirements of this subchapter for the purpose of performing any other process control duties in the distribution or treatment facilities of a public water system.(d) An individual who holds a groundwater or surface water license may perform duties relating to the operation and maintenance of drinking water production, purchased water, and water distribution systems and is not required to hold a distribution license.