The Integrated Water Supply Scheme (IWSS) is the largest scheme we manage. The IWSS delivers 309 billion litres of water each year to over 2 million people. The distribution network includes Perth, the Goldfields and Agricultural Region and parts of the South West.

The IWSS is made up of the following water sources:

  • desalinated seawater
  • groundwater
  • dams
  • groundwater replenishment

In future, more water will come from seawater desalination, secure groundwater sources and groundwater replenishment. There will be less reliance on our dams. 

A new desalination plant is being built in Alkimos. The Alkimos Seawater Desalination Plant (ASDP) will have the capacity to supply 100 billion litres a year of drinking water. The first stage will be operational in 2028. 

Stage 2 of the Groundwater Replenishment Scheme was completed in 2022. The second stage doubles the capacity of the Beenyup plant. Up to 28 billion litres of treated wastewater can be recharged into groundwater supplies each year.

Learn more about Perth’s water supply with our interactive tool.

We've developed a long-term plan to ensure our future generations have a secure water supply. Learn more about our goals for 2050.