A method described in this report uses the time concentration profile from the discharging well of a labeled recharging‐discharging well pair to evaluate an aquifer's porosity and dispersion constant. The technique is applicable for pulse tracer injection and recirculation. Derived equations allow prediction of streamline arc lengths and travel times between wells along streamlines. Adjacent streamlines joining the two wells define crescents that approximate dispersion columns of known length. The summation of breakthrough curve concentration profiles for flow through these individual columns provides a composite breakthrough curve for the entire flow field. Analysis of a tracer test using tritium in a fractured carbonate aquifer near Carlsbad, New Mexico, provided a dispersion constant of 125 feet and a porosity of 12.0%, values consistent with known properties of the aquifer.