Managing Water Quality in Distribution Networks

<p dir="ltr">Uisce Éireann (UE – Irish Water) upholds high water quality standards in compliance with European Union regulations. However, due to the ageing network assets and unplanned changes in flow patterns such as increases and reversals, customers occasionally experience episodes of discoloured water. (Note: The names of water supply zones and DMAs have been anonymised at UE’s request.) Within Water Supply Zone (WSZ) “A”, several DMAs have recorded a high number of water quality contacts. Among them, the DMA XYZ has been identified as the poorest performing in terms of discolouration incidents. To investigate the root causes, a comprehensive analysis was conducted using hydraulic and water quality modelling, supported by field sampling. The findings indicated that a combination of factors including pipe material, oversized mains, and source water characteristics likely contributed to the discolouration events. To address these issues and optimise DMA performance, a three stage intervention strategy was developed, alongside adjustments to source water chemistry. This strategy included: • Immediate mitigation through proactive and reactive flushing to reduce customer complaints. • Sustained improvement through mains conditioning, including trunk mains; and • Long term enhancement through mains rehabilitation to resolve underlying water quality issues and improve network efficiency. DMAs were prioritised for intervention based primarily on rankings derived from water quality contact data and pipe material assessments. However, public and political pressures also influenced the final order of implementation.</p><p dir="ltr">This paper was presented at the 21st Computing and Control in the Water Industry Conference (CCWI 2025) at the University of Sheffield (1st - 3rd September 2025).</p>