Evaluation and Management of Water Losses in Water Distribution Systems: Towards the Implementation of Directive (EU) 2020/2184

In accordance with the provisions of Directive (EU) 2020/2184, the largest water supply companies in the European Union (EU) will be required to report real water losses starting from 2026. The recommended water loss performance indicators (PIs) are the infrastructure leakage index (ILI) rating method or “another appropriate method”. The article presents results of research aimed at examining the relationship between the ILI and other selected PIs for water losses in selected Polish water distribution systems (WDSs) located in southern Poland. The highest values of determination coefficients for the linear relationships between the ILI and PIs were obtained in the case of intermediate normalized PIs for real losses expressed both as a volume of water per km of mains per 1 m H2O of pressure (R2 = 0.951) and as a volume of water per service connection per 1 m H2O of pressure (R2 = 0.9365). A very strong linear correlation with the ILI was also obtained in the case of basic normalized PIs for real losses, expressed as the volume of water per service connection (R2 = 0.7336). The moderate linear correlation was detected in the case of the percentage PIs for water losses. Results show that the recommended indicators, which can be used when the ILI cannot be calculated, should be the intermediate or basic operational normalized indicators.