We present a methodology and results for measuring crystallization kinetics of sparingly soluble salt mixtures typical of reject/concentrate streams from membrane-based, inland water supply processes. More usable water can be recovered (and lower disposal costs incurred) from these concentrate streams through efficient crystallization. In this work, we present a steady state, continuous stirred tank reactors (CSTRs)-in-series approach to study crystallization kinetics of a model solution mixture that is supersaturated in CaCO3. We have used pH, conductivity and turbidity changes in the system to monitor crystallization using six CSTRs with individual residence times of nominally 3, 5, and 11 min. This system operates in a steady state mode with total crystallization times from similar to 15-68 min and was capable of handling up to similar to 0.59 L/min of hard water for the shortest residence time studied. The supersaturation was depleted similar to 25% and over 50% with total reactor system residence times of similar to 15 and 68 min, respectively, without any added chemicals. Using the metric of 5 NTU turbidity as being the point of discernible crystal formation, we examined how mixing energy dissipation affects the induction times for crystallization. Notably, discernible crystallization could only be advanced to the 1st CSTR by using a recirculation loop to "fine-tune" the effect of surface area exposure-to-volume ratio, as well as, mixing energy dissipation. A rudimentary, semi-empirical model was used to capture the parametric trends of our experimental results, using the Kolmogorov mixing lengths, surface area-to-volume ratios, flow rates, and nominal diffusion coefficients. This parameterization may be tested further for design scale-up guidance.