Navigate home logo

Over the years, Perth has experienced a remarkable transformation in securing its water supply. But the journey hasn’t been an easy one. 

Hot summers and drier winters have resulted in an 80% reduction in streamflow into Perth’s dams. What was once a generous 420 billion litres of streamflow per year has now shrunk to just 77 billion litres per year.

Unlike our eastern state counterparts, Perth can no longer rely on rainfall alone to meet our water needs. Our unique climate has led us to develop innovative new ways to sustain our water supply.

Desalinated water – a first for Australia

In 2006, we reached a ground-breaking milestone as the first Australian utility to mass-produce desalinated seawater with the opening of the Perth Seawater Desalination Plant. Today there are 6 large-scale desalination plants in Australia - two of which are in WA, with plans for a third underway.

Desalinated seawater accounts for around 30-40% of Perth's drinking water in any given year (depending on rainfall and streamflow). From 2007 to 2023, WA's desalination plants produced 1,533 billion litres of fresh drinking water - enough to fill Optus Stadium 1,533 times! 

Perth Seawater Desalination Plant
Perth Seawater Desalination Plant, located in Kwinana. 

Groundwater in the mix

Groundwater has also taken centre stage in Perth's water mix, accounting for 30-40% of our scheme water. However, even groundwater isn't immune to the effects of dwindling rainfall. 

Our plans for a third desalination plant in Perth, along with the wider allocation changes introduced by the WA Department of Water and Environmental Regulation, will promote the future sustainability of groundwater in Perth's north. 

Wanneroo Groundwater Treatment Plant
Wanneroo Groundwater Treatment Plant.

World-leading solutions

Our innovation doesn't stop at desalination. We're leading the world in groundwater replenishment

This ground-breaking process takes treated wastewater and purifies it to drinking water standards before recharging it into our groundwater supplies.

The aquifers act as natural filters and reservoirs, storing purified water for years to come, supplementing our public drinking water supplies.

Currently, groundwater replenishment makes up approximately 3-8% of Perth's drinking water supply. 

Our biggest challenge to long-term water security 

Streamflow (also known as rainfall runoff into dams) is still a vital component of our water supply. However, this is significantly lower to other Australian cities, where rainfall plays a far more substantial role in water supply. 

Unreliable rainfall and streamflow are the key drivers behind our changing water availability and remains the single biggest challenge to our long-term water security in southern Western Australia - particularly for Perth and its southern regions.  

What sets us apart? 

In the face of these challenges, our team of expert water source planners are dedicated to ensuring that Perth continues to enjoy a secure and sustainable water supply.  

While it's true that Perth's unique water source mix requires different treatment to other states, the water we supply meets (and can sometimes exceed) the necessary standards under the Australian Drinking Water Guidelines - which are some of the most robust in the world. 

Perth's journey towards water sustainability is an ongoing tale of innovation and resilience and we remain committed to providing a secure water supply for Perth and Western Australia.