The foundational assumptions underpinning urban stormwater management in Australia are being systematically invalidated by anthropogenic climate change. This report establishes that the escalating frequency and intensity of extreme rainfall events are rendering historical engineering paradigms obsolete, creating a new and rapidly growing risk of on-property and cross-property flooding for households in cities like Sydney. The analysis reveals a critical and widening mismatch between the design capacity of aging, often deteriorating, public stormwater assets and the unprecedented hydrological loads they are now expected to manage.
This systemic failure results in a cascade of severe socio-economic consequences, including catastrophic property damage, a burgeoning insurance affordability crisis, profound housing insecurity, and significant psychological trauma for affected communities. The report argues that the traditional, fragmented approach to water management—where stormwater, wastewater, and water supply are treated as separate domains—is no longer tenable. In its place, this report presents a comprehensive, multi-scalar framework for adaptation and resilience.
This framework integrates actions across federal, state, and local government levels, while simultaneously empowering homeowners and developers to transform individual properties into active components of a distributed, catchment-wide green infrastructure network. The core recommendation is for a paradigm shift from a reactive, conveyance-based model of stormwater disposal to a proactive, integrated system of water management that prioritizes infiltration, storage, and reuse. This transition is not merely an engineering necessity but a critical investment in the future liveability, sustainability, and economic viability of urban Australia.
