Systems and methods for preventing water from freezing in a spa or hot tub featuring a spa pack having a pump, heater and controller connected to a spa power supply through a ground fault circuit interrupter. A sensor is used to monitor an operating condition of the spa pack that is initially electrically connected to the spa power supply in order to activate at least one freeze prevention device if the operating condition of the spa pack changes due to electrical disconnection from the spa power supply by the ground fault circuit interrupter. The freeze prevention device features a heater, a circulating pump or both, and keeps water in the tub and the piping associated therewith from freezing. A switching arrangement is provided for deactivating the system outside the winter season when freeze protection is not required.