Improved Representation of Water Age in Distribution Networks to Inform Water Quality

Abstract

Mathematical simulation models that are used to provide information about the age of water in potable water distribution networks usually represent the age of water as the flow weighted average age value of the merged flows at a particular location. This approach is questioned and it is argued that age values should not be averaged in this way. This paper describes a methodology to improve the description of the age of water by using the outputs from a simulation model to identify the component ages that contribute to the mean age. In this case, the AQUIS software was used as the simulation engine and the model has been enhanced to calculate the volume and age of the different parcels of flow that meet at all nodes in the network. The program has then been adapted to subsequently track these parcels of water throughout the network. The model provides a description of the component age profiles at any point in a distribution network and this information can be translated into operational strategies to manage the flows, and hence residence times, thereby providing the opportunity to improve overall water quality performance by identifying potential water quality problem areas and hence to promote proactive remediation strategies. The paper is concluded by a case study example of the application of the model.