Modeling and Field Work to Investigate the Relationship between Age and Quality of Tap Water

Abstract

It has been widely theorized that water age may be a useful indicator of the quality of water within drinking water distribution networks. However, there is limited evidence of model simulation results being related to empirical water quality (WQ) data to substantiate the theory. This paper presents the findings of investigations designed to determine if there was an observable relationship between mean water ages calculated using a WQ simulation model, and measured WQ in two live distribution networks. The age of water in all pipes was calculated using Aquis hydraulic and WQ modeling software. Historic regulatory WQ data was examined to determine if there was a relationship between general WQ and calculated water age within the networks. A more detailed study was then undertaken in one network by translating model locations that were representative of the spread of water age into real-world locations. WQ samples were taken intensively from these sites and analyzed for a range of aesthetic, physical, chemical, and bacteriological parameters indicative of general WQ. Some relationship between the calculated mean age of water and the general WQ in the network was demonstrated. Analysis that considered calculated water age and associated WQ along unperturbed flow routes through the network produced a stronger relationship. Given that regulatory WQ within the study networks as reported to the Drinking Water Inspectorate (DWI) was 99.9 percent compliant, this relationship was deemed noteworthy.