A permanent structural decline in rainfall and stressed groundwater aquifers mean Perth relies entirely on expanding energy-intensive desalination to secure its drinking water.
The most profound physical impact of climate change on Western Australia over the past half-century has been a structural shift in weather patterns. Since the 1970s, the south-west of the state, including the Perth metropolitan area, has experienced a severe and sustained decline in winter rainfall — the crucial runoff that historically filled the region’s drinking water dams.
In previous generations, the hills dams functionally held the entirety of Perth's drinking supply. Today, surface water runoff into these catchments is so consistently poor that the dams effectively operate as holding tanks rather than primary generation sources. Perth is deeply reliant on climate-independent water sources just to maintain basic civic function and supply the sprawling suburban garden culture.
Historically, when the dams failed, Perth leaned heavily on the Gnangara Mound, a massive, shallow groundwater system sitting beneath the northern suburbs. But decades of over-extraction by both the municipal water scheme and huge allocations to local agriculture, industry, and council parks have pushed the aquifer to a state of structural stress. Environmental regulators are actively clawing back groundwater allocation limits to prevent the permanent ecological collapse of the wetlands and native bushland that rely on the mound's water table.
With dams obsolete and groundwater extraction being aggressively throttled back, Perth's future survival is entirely anchored to seawater desalination. The network currently operates two massive, baseload desalination plants (at Kwinana and Binningup) which provide roughly half of the city's drinking water, supplemented by a pioneering groundwater replenishment scheme that treats wastewater and injects it back into deep aquifers.
However, population growth and continual climate drying mean surface and groundwater sources are further shrinking. The state is currently undertaking the massive construction of a third major desalination plant at Alkimos in the northern suburbs just to secure the baseline supply for the next decade.
Desalination is inherently energy-intensive. As the state government attempts to decarbonise its electricity grid (closing coal plants), the primary friction point is ensuring that the massive energy drain required to continuously force seawater through reverse-osmosis membranes is powered by renewable generation, rather than further straining the gas-fired network during peak summer demand.