Integrated water supply scheme
The Integrated Water Supply Scheme (IWSS) is our largest water supply network. It provides clean and safe drinking water to over two million people in Western Australia.
But the IWSS is more than just pipes and pumps. It’s a carefully managed network that connects water from different places across the state. In 2023–24, it sourced a total of 332 billion litres of water, with 328.8 billion litres supplied to homes, schools, farms and businesses. The remainder supported operational activities and riparian releases to help maintain downstream river ecosystems.
Many people think the IWSS only supplies water to Perth, but it actually reaches much further. It also supports the Peel region, Goldfields and Agricultural Region, parts of the South West and the Upper Great Southern. The IWSS includes the Goldfields and Agricultural Water Supply (GAWS) and the Great Southern Town Water Supply Scheme (GSTWSS), which help deliver water across these broader areas.
To make all this possible, the IWSS uses a mix of water sources and facilities. These include 15 dams for storage, six groundwater treatment plants, a groundwater replenishment plant and two desalination plants.
In addition, we supply recycled wastewater through our Wastewater Resource Recovery Facilities (WRRF) for commercial use reducing the demand on our precious water supply. WRRFs are changing how we view wastewater. These facilities don't just treat waste. They also help us recover valuable resources, such as recycled water, biosolids and biogas. These can be used again in parks, urban forests, wetlands, farms and certain industries.
Each part of the IWSS plays a key role in making sure we have safe, reliable water now and into the future.
Our climate has experienced significant change in the last 100 years, so we've had to adapt and change too. By utilising streamflow, groundwater, desalinated seawater and recycled water, we have met the water needs of over 2 million residents. Our dams and reservoirs store a mix of these water sources. Though it's important to note that groundwater is generally not stored in dams. Instead, it is treated and either distributed directly to customers or stored in reservoirs before being supplied. To help show just how far the IWSS reaches, take a look at the map below.
Planning for the future
As our climate continues to change, we’ve shifted away from relying on streamflow and rainfall and investing in more climate independent sources.
We’re always thinking ahead. Our long-term plans are focused on building a climate-independent water future, one that can support WA’s growing needs for generations to come.
That’s why we have several major projects underway. Each one is designed to strengthen our water supply, adapt to changing conditions and ensure safe, reliable water for the future.
Major projects underway
Alkimos Seawater Desalination Plant (ASDP)
A new desalination plant is under construction in Alkimos. In its first stage, it will provide up to 50 billion litres of water each year. To make sure this water reaches homes and businesses, we’re also building a new pipeline that will connect the plant to our IWSS. This helps us share the water across the region and keep the supply strong and reliable.
Groundwater Replenishment Scheme – Stage 2
Completed in 2022, this project doubled the capacity of the Beenyup Advance Water Recycling Plant. Now, up to 28 billion litres of recycled water can be safely recharged into our groundwater supplies each year.
What can I do to make a difference?
Understanding where our water comes from and the challenges we face is the first step toward making a real impact. By being mindful of how we use water, each of us can contribute to a more sustainable future.
Simple changes in your daily routine can make a big difference: taking showers that last no more than four minutes, sticking to your watering days, fixing leaks promptly and choose water-efficient appliances. Consider creating a waterwise garden to further reduce your water footprint.
Together, we can help Western Australia thrive, even as we face the realities of climate change. Let’s protect our water supply and preserve the unique lifestyle we enjoy here in WA.