Pressure dependent analysis (PDA) is preferred over normal demand dependent analysis (DDA) to evaluate the performance of the network under pressure deficient conditions. The PDA requires a relationship, called node-head-flow relationship (NHFR) between available head and available flow at a node to know whether the demand is fulfilled completely, partially or not at all, depending on the available pressure. Several NHFRs have been suggested in the past. An assessment of these NHFRs have been made by considering some real-life networks, wherein demands of several consumers located at different elevations are lumped. Herein, the secondary networks of minimum pipe sizes taking-off from a node on the primary networks are analysed by considering different heads at the off-taking point and variation of total supply from the off-taking point is plotted against available heads considered at that point. This provided the actual variation and thus considered as the observed NHFR at the node of a primary real-life networks. Different NHFRs reported in the literature are then used to predict the outflow in secondary network at different available pressures. Evaluation of NHFRs is carried out by calculating errors in prediction using chi square for their effectiveness in prediction. It is observed that actual NHFR is not that smooth as the approximated by the different NHFRs. Nonlinear behaviour between available flows and available heads for partial flow conditions is observed to be the best in most of the cases with proper values of constants in defining NHFR. This assessment recommends consideration of different NHFR at different nodes of the primary network for PDA considering the nature of pressure requirement in secondary network of lumped demand nodes.