A hydrotherapy system uses a plurality of water sources, each of which produces water at a fixed temperature. The water from the fixed temperature sources can be mixed to form several mixed water streams, each with a predetermined temperature, by an array of computer-controlled on-off solenoid valves. Solenoid valves can also be used to apply the mixed water streams with different flow rates selectively to different body zones. The solenoids are controlled via sequences that can be created and maintained with an intuitive graphical user interface.