Rainfall & dams
Our water overview
Updated: Monday, 27 October 2025
Learn more about how this data is updated
* Average monthly rainfall (for the period 1876 - 2016).
Dam volumes, rainfall and water use data is updated every working day, streamflow is updated weekly.
How declining rainfall impacts our water supply
We need steady, regular rain in order to soak our catchments and get water flowing into our dams. Slowly declining rainfall means Perth's dams receive much less streamflow than in past years. Streamflow is the amount of water entering our dams from our catchments and is measured by changing water storage levels.
The water in our dams is no longer just made up of inflows from rain. Groundwater and desalinated water are stored in these dams during periods of low demand so it is available when it is most needed in the hotter months.
Learn more about how the impact of climate change continues to affect rainfall, the streams that flow into our dams and water use.
Perth's water sources at a glance
In 2023-24 the breakdown of Perth's water sources (IWSS) consisted of:
%
Desalination
%
Groundwater
%
Dams
%
Groundwater replenishment
Latest dams & rainfall news
23 Oct 2025
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Media Release
Local wildlife makes a splash in Oakford for National Water Week
An inquisitive Australian ringneck and a young kangaroo are among local wildlife showcased on a new mural in Oakford under Water Corporation’s public art program, Splash of Colour.
22 Oct 2025
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Media Release
Waterwise Albany schools to save millions of litres of water
Seven Albany schools are aiming to save an impressive 2.6 million litres of precious drinking water each year - equivalent to 62 backyard swimming pools - thanks to a Cook Government program.
