The development of new adsorbent materials for the removal of toxic contaminants from drinking water is crucial to achieving the United Nations Sustainable Development Goal 6 (clean water and sanitation). The characterisation of these materials includes fitting models of adsorption kinetics to experimental data, most commonly the pseudo-second order (PSO) model. The PSO model, however, provides no sensitivity to changes in experimental conditions such as adsorbate and adsorbent concentrations (C 0 and C s ) and consequently is not able to predict changes in performance as a function of operating conditions. Furthermore, the experimental conditionality of the PSO rate constant, k 2 , can lead to erroneous conclusions when comparing literature results. In this study, we analyse 108 kinetic experiments from 47 literature sources to develop a relatively simple modification of the PSO rate equation, yielding:Unlike the original PSO model, this revised rate equation (rPSO) demonstrates the first-order and zero-order dependencies upon C 0 and C s that we observe empirically. Our new model reduces the residual sum of squares by 66% when using a single rate constant to model multiple adsorption experiments with varying initial conditions. Furthermore, we highlight how the rPSO rate constant k' is more appropriate for literature comparison, highlighting faster kinetics in the adsorption of arsenic onto alumina versus iron oxides. This revised rate equation should find applications in engineering studies, especially since unlike the PSO rate constant k 2 , the rPSO rate constant k' does not show a counter-intuitive inverse relationship with the increasing reaction rate when C 0 is increased.