Tempered water mixing system

A tempered water mixing system for applications such as emergency drench shower and eyewash stations, wherein the mixing system includes back-up control valves to ensure a substantial water flow without risk of user scalding in the event of malfunction of a main thermostatic mixing valve. The main mixing valve thermostatically blends cold and hot water supplies to provide a tempered discharge outflow at a selected temperature. A temperature limit control valve detects the discharge outflow temperature and responds to an excess temperature condition to modulate hot water flow in a manner reducing discharge temperature. A flow limit control valve detects the pressure differential between the discharge outflow and the cold water supply, and responds to a low flow condition represented by a high pressure differential to permit a make-up bypass flow of cold water past the main mixing valve.