A method and system for supplying temperature-controlled water to emergency shower and/or eyewash units ("SS/EWs"). In one embodiment, the water is circulated through a normally closed system containing a heat source such as a heat exchanger, a tank and pipes leading to the SS/EWs. Sensors in the system detect the temperature of the water and controllers regulate the amount of heat supplied to the heat exchanger to keep the temperature of the water in the system within a desired range of temperatures. A timer-controlled drainage subsystem periodically drains some or all of the water in the system. Water drained or supplied to the SS/EWs is made up by a cold water supply that feeds the heat exchanger. The system may use an alarm to signal water out of the desired temperature range, improper drainage, or water leaking from the system or being used by an SS/EW.