Reducing Non-revenue water as a climate adaptation strategy in water-scarce and fragile contexts: evidence from Aden, Yemen

ABSTRACT Water scarcity in fragile and conflict-affected settings is increasingly exacerbated by climate variability, rapid urbanization, and infrastructure deterioration. In such contexts, reducing Non-Revenue Water (NRW) represents an immediate and low-cost opportunity to enhance water security without developing new water sources. This study assesses water losses in the urban water supply system of Aden, Yemen, using an IWA-standard water balance combined with field-based meter testing, unauthorized consumption assessment, and economic analysis. While NRW was 42.6% of system input volume in 2020, the analysis shows that apparent losses – primarily associated with illegal consumption and meter inaccuracies – constituted the dominant component, followed by real losses from leakage in an aging and intermittently operated network. After normalization to a continuous-supply basis, the Infrastructure Leakage Index of 11.0 (World Bank Institute Band C) and the Apparent Loss Index of 10.4 indicate poor system efficiency under intermittent supply conditions. Economic analysis demonstrates that reducing water losses to their economic level could recover approximately 7.3 million cubic metres of water annually – comparable in volume to the desalination capacity proposed as the city's supply-side adaptation – effectively increasing available supply without additional abstraction. The findings highlight NRW reduction as a viable climate adaptation and water security strategy for water-scarce cities in fragile and conflict-affected contexts, with direct implications for utility management and policy.