5 Colo. Code Regs. § 1003-5-4.12
The sewer system shall be adequate to serve the facility, including bathhouse, looker room and related accommodations. The sewer line serving the backwash for the filter shall be 1-1/2 times the size of the backwash line or provide a containment vessel capable of holding a minimum of 5 minutes volume of backwash water at the backwash design rate.
There shall be no direct physical connection between the sewer system and any drain from the swimming pool or recirculation system. Any swimming pool, gutter drain, overflow from the recirculation system when discharged to the sewer system shall connect through a suitable air gap so as to preclude the possibility of backflow of sewage or waste into the swimming pool piping system.
The sanitary sewer serving the swimming pool and auxiliary facilities shall discharge to the public sewer system wherever possible. Where no such sewer is available, the method of disposal shall be in accordance with the requirements of the Colorado Department of Health or local health department.
5 CCR 1003-5-4.12