Urban water distribution systems in many Asian megacities continue to exhibit high Non-Revenue Water due to fully buried and physically inaccessible networks. This study examines how infrastructure accessibility moderates the relationship between Hydraulic and Structural Risk Factors and real losses in dense urban systems. Accessibility—operationalized through walkable utility corridors and monitoring density—is incorporated as a moderating factor of leakage accumulation within a causal analytical framework. A comparative analysis is conducted across five Asian cities representing a gradient of accessibility: Singapore, Tokyo, Hong Kong, Kuala Lumpur, and Jakarta. Results show that while Hydraulic and Structural Risk Factors varies only modestly across cases, real losses differ by more than an order of magnitude, from about 61,000 m³/day in Singapore to 700,000–1,000,000 m³/day in Jakarta and Kuala Lumpur. In four of the five cities, accessibility explains over 70% of modelled real losses and remains the dominant factor even in low-Non-Revenue Water systems such as Singapore (≈5–6%). Sensitivity analysis indicates that a +0.10 increase in accessibility reduces modelled real losses by 10–15% without changes to pressure or pipe materials. The findings confirm that hydraulic and structural risk factors set leakage potential, while accessibility governs loss accumulation through leak duration and observability.
Plamonia et al. (Wed,) studied this question.