What is the Integrated Water Supply Scheme?

The Integrated Water Supply Scheme (IWSS) is the largest scheme we manage. It delivers 312 billion litres of water each year to over 2 million people in Perth, the Goldfields and Agricultural region and some parts of the South West.

In 2017–18 water supplied into the IWSS came from the following sources:

  • 48% desalinated seawater
  • 40% groundwater
  • 10% surface water (from our dams - this water can also contain a proportion of water that originated from groundwater or desalination, as we bank water from these sources in our dams)
  • 2% groundwater replenishment

In future, less water will come from our dams and more from desalination and secure groundwater sources. We have developed a long term plan to ensure future generations have a secure water supply. Learn more about our goals for 2030.