Hydraulic modelling is considered an important tool in the planning and operational decision for a water supply network. Technological advances made a number of evolutions in this field and real time operational modelling is a recent addition. Hydraulic modelling tools have been used extensively for earthquake recovery and what/if investigations in the post-earthquake Christchurch. A number of rebuild strategies have been modelled as part of post-earthquake recovery work. Rezoning (smaller pressure zones reduced pressure) of water supply network is proposed to make the network less vulnerable to earthquakes. Rezoned water network was tested using sophisticated hydraulic modelling tools (with real time automatic control systems) and results are reported in this paper. A pilot field study was conducted on future rezoned network to validate the findings of hydraulic modelling study and the findings are also summarised in this article. The field study pointed out a number of low pressure related issues that the hydraulic modelling tools were unable to predict properly. As the model was calibrated using flow and pressure data collected from trunk main infrastructure, it was unable to predict pressure correctly at individual properly boundaries. A real time hydraulic modelling tool can be a better option for earthquake damage assessments in real time and also to test earthquake vulnerability of a proposed water network. Real time modelling will potentially help to reduce surprises or unusual finding during real time data collections and field-studies.