NRW benchmarks, ILI interpretation, real losses vs. apparent losses, and economic level of leakage calculation.
What is an acceptable level of non-revenue water (NRW) for a water utility?
The International Water Association benchmarks well-run utilities at 10–20 % NRW as a proportion of system input volume. In MENA, utilities with aging infrastructure typically report 25–40 % NRW. The IWA Infrastructure Leakage Index (ILI) is a more nuanced measure — an ILI ≤ 1.5 is considered excellent for systems under 50 m pressure. Economic level of leakage (ELL) analysis, rather than a fixed percentage, determines the optimal NRW reduction investment in each system.