Abstract: An apparatus and method for prompting a person using a shower to conserve water includes a shower temperature sensing and signal producing unit for mounting on a shower pipe to sense when hot water arrives in the shower pipe and to signal the shower user that the hot water has arrived, thus time to start showering. The apparatus includes a housing that clamps onto the shower pipe, and a heat conducting pin conducts heat from the shower pipe outside the housing to a temperature sensor inside the housing, where the temperature is sensed and transduced to electrical signals that are processed to produce the signals to the shower user. The apparatus is portable and self-actuating so that it can be moved from one shower to another without any switching on or off or adjustments.