Rainfall has dramatically decreased in many areas of our state. Since the 1970s May to July rainfall in the south west of WA has reduced by around 20 per cent State of the Climate 2018, Bureau of Meteorology.

Given this, the sources of water for our largest scheme - the Integrated Water Supply Scheme* - have changed dramatically. The amount of streamflow to our dams generated from each millimetre of rainfall continues to decline.

Before 1975, Perth’s dams would receive an average of 420 billion litres of streamflow each year, enough to supply the scheme even now. In comparison, during 2019 Perth’s dams received just 44 billion litres of streamflow.

In 2015, Perth’s dams received the lowest level of streamflow since records began in 1911 – with just 15.9 billion litres of water. To put that into perspective, that’s only enough water to supply Perth for around 15 hot summer days.

Water Corporation has been responding and adapting to climate change to secure water supplies for generations to come, by continually working towards our long-term targets outlined in Water Forever, first published 10 years ago. This plan adopts a three pronged approach, which includes:

  • Working with the community to reduce water use to help defer the need for investment in further new climate independent sources;
  • Developing new water sources; and
  • Increasing the amount of water recycled.

Water for the Integrated Water Supply Scheme is now comprised of a combination of sources, including desalinated seawater, groundwater, groundwater replenishment and streamflow into dams.

What we’ve achieved so far

Nearly half of the water used by our customers connected to the Integrated Water Supply Scheme can now be manufactured – independent of rainfall.


Perth has two desalination plants - the Perth Seawater Desalination Plant in Kwinana and the Southern Seawater Desalination Plant in Binningup – which can produce up to a combined 145 billion litres of water each year if required.

The Perth Seawater Desalination Plant began producing drinking water in late-2006 and was the first large-scale plant in Australia. It was the largest desalination plant in the southern and eastern hemispheres when constructed, and can produce up to 45 billion litres of drinking water a year.

In January 2013, Southern Seawater Desalination Plant began producing drinking water. This plant has the capacity to produce 100 billion litres of drinking water each year – direct from the Indian Ocean.  

Australia’s first Groundwater Replenishment Scheme

Did you know Perth is home to Australia’s first Groundwater Replenishment Scheme? Later this year, work will be completed on the second stage of our Groundwater Replenishment Scheme, which means the scheme will be able to produce up to 28 billion litres of water each year if required. 

Groundwater replenishment ticks two of the boxes outlined in Water Forever it provides a new, sustainable and climate independent water source, and an increase in water recycling.

Groundwater replenishment is an innovative process where highly treated wastewater undergoes advanced treatment to produce recycled water equivalent of drinking water quality. This water is then recharged to an underground aquifer, where it is ‘banked’ for later use as a drinking water source. Once the water is drawn out of the aquifer, it is further treated in the same process as groundwater is usually treated, and added to the drinking water supply scheme.

Construction of the first stage of the Groundwater Replenishment Scheme in Craigie (north of Perth) was completed in late-2017 and has the capacity to recharge up to 14 billion litres of recycled water to aquifers each year.

Our scheme in Perth was modelled on a similar scheme operating in Orange County, California, since the 1970s. If you have ever visited Disneyland in California, chances are you tasted this recycled water!


Traditionally, Perth relied heavily on streamflow into our dams as a water source, but declining streamflow has meant dams now play a bigger role as storage reservoirs.

We now ‘bank’ water produced through desalination and groundwater in its dams during the cooler months when demand is lower.

What can the community do?

Our Water Forever plans include working with the community and businesses to reduce water use. Reducing water use offers a cost effective and environmentally responsible option to reduce demand on scheme water supplies and potentially defer major capital expenditure.

Water saving efforts in Perth since 2001 helped save around 122.2 billion litres of water in 2017-18 – to put that into perspective, that’s more water than WA’s largest desalination plant produces each year!

By using water wisely, the community can help to defer the need for new water sources. Find out how you can save water.

*The Integrated Water Supply Scheme delivers drinking water to more than two million people in Perth, the Goldfields and Agricultural region and some parts of the South West each year.

Climate change news

23 Jul 2020 | Media Release

Denmark pipeline construction gets under way

Water Corporation is well on the way to further securing Denmark’s water supply as construction work has started for the new pipeline that will connect the town to the Lower Great Southern Town Water Supply Scheme.

  • Climate change
  • Denmark
02 Jul 2020 | Media Release

Local governments leading the way towards a Waterwise WA

Water Minister Dave Kelly has commended local governments for their commitment to developing sustainable, liveable communities and leading the way towards a Waterwise WA.

  • Climate change
  • Community
  • Waterwise
05 Jun 2020 | Update

Water Corporation makes permanent changes to protect our environment

This UN World Environment Day, we’re taking time to celebrate nature, raise awareness of its importance and share a few of the ways in which we’re giving back.

  • Climate change
  • Environment
  • Community
Driving down net vehicle greenhouse gas emissions
04 Jun 2020 | Media Release

Denmark pipeline to deliver local jobs

Water Minister Dave Kelly has announced the Water Corporation is on track to deliver the pipeline from Albany to Denmark in early 2021.

  • Climate change
  • Community
29 May 2020 | Media Release

A decade of water saving celebrated as annual Winter Sprinkler Switch-off returns for 2020

Households and businesses across Perth, Mandurah and parts of the South-West and Great Southern are being reminded to help save billions of litres of precious water by turning off their sprinklers this winter.

  • Residential
  • Climate change
  • Community
  • Irrigation
  • Waterwise
28 May 2020 | Media Release

Water Corporation moves to greener fleet with electric vehicles

Water Corporation is today introducing two full-electric vehicles (EVs), the first of a wider commitment to further reducing carbon emissions and minimising its environmental footprint.

  • Climate change
26 May 2020 | Media Release

Green light for world-leading renewable hydrogen from wastewater project

For the first time in Australia, a project is in the pipeline to produce low-emission hydrogen and graphite from sewage at a wastewater treatment plant.

  • Wastewater
  • Climate change
Woodman point wastewater treatment plant