A decades-long decline in rainfall and depleted groundwater aquifers have made Perth heavily reliant on large-scale seawater desalination.
Water security is a silent but persistent force shaping policy across the broader Perth metropolitan region. Located in a drying climate zone, Western Australia’s southwest has seen a steady and dramatic decline in winter rainfall over the last half-century, fundamentally changing how the city sources its water.
Historically, Perth relied heavily on its natural dams and shallow groundwater aquifers (such as the Gnangara Mound) for residential and agricultural supply. Decades of reduced rainfall and suburban expansion have severely depleted these sources. The state is currently undertaking delicate regulatory balancing acts to reduce groundwater extraction allowances for local councils, agriculture, and industry, seeking to stabilize the sinking water table that supports local wetlands and suburban tree canopies.
To insulate the city from the drying climate, Perth has become highly dependent on climate-independent water sources. Large-scale seawater desalination plants currently supply roughly half of the city's drinking water, a proportion that is projected to grow. Additionally, advanced groundwater replenishment schemes—treating wastewater to drinking standards and pumping it back into deep aquifers—form a massive part of the region's hidden infrastructure.
Desalination is highly energy-intensive. A key environmental friction point is ensuring that the heavy power requirements of new and existing desalination plants are met by renewable energy rather than the fossil fuels that exacerbate the underlying climate shift. Furthermore, residents in the city's expanding footprint face tightening restrictions on how and when they can water their gardens, sparking ongoing debate about urban design in a chronically dry environment.