The portable pressure recorder is an instrument for collecting time-dependent pressure data to be used to calibrate and validate steady-state and extended-period computer models. Also, its ability to measure rapid pressure changes over time with good accuracy and resolution makes it useful in the investigation of transient water system phenomena. The recorders are also useful in the field troubleshooting of water systems to document pressure activity which may otherwise be undetected. The instrument consists of a pressure transducer, a solid state data logger, and a small, portable power supply. The water supply is attached through a fitting to the transducer; details are given on programming the data logger and built-in clock, configuration with blowoff valves and Bourdon gages, and so forth. Uses of the recorder vary from calibration of models, measuring valve operating speed, wave period and speed, head loss tests, hydrant flow tests, and others.