Abstract: Disclosed is a septic heater system and method for preventing a freeze-up in a septic system. The heater system typically is used with a previously-installed septic system that includes a septic tank, drop boxes, connecting sewer pipe, a drainfield, and one or more vertical access/cleanout pipes which rise from one or more portions of the septic system to corresponding access ports at ground level. The heater system, which is adapted for connection to the access ports of one or more of the vertical access clean-out pipes, comprises a heater and fan system defining an output port for providing a flow of heated air at the heater output port. The heater output port is defined by a structure configured for coupling the output port to one or more of the access/cleanout pipes. The heater and fan system, when activated to provide the flow of heated air and when coupled to an access/cleanout pipe, prevents septic-system freeze-up by delivering the heated air down the access/cleanout pipe to the septic system.