Validation of the source redshift distribution decomposition for DNF (top) and BPZ (bottom) source redshift estimates. In different richness (color coded) and redshift bins (different panels), we show the difference between the source redshift distribution measured along the cluster line of sights and the field distribution extracted at a safe distance from the cluster center, shown as stars. Both are shown here for the projected cluster-centric distance of 1 Mpc in our reference cosmology. The resulting increment is well modeled by a Gaussian component (lines) caused by the cluster members contaminating the source sample. The amplitude of this component scales with cluster richness.