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 volumes.

The water in our dams is no longer made up of just streamflow 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.

Our water overview

Updated: Friday, 26 November 2021 Learn more about how this data is updated

To 9am

0.00

mm

May total

May average*

32.20

mm

88.70

mm

Current

42.5%

268 GL

Last year

45%

284 GL

Change

5.7%

-16.2 GL

* Average monthly rainfall (for the period 1876 - 2016).
Dam volumes, rainfall and water use data is updated every working day, streamflow is updated weekly.

Total dam levels

Total Dam Capacity

Perth Metro
62.8%
395.64 GL
Last year
49.8%
314.02 GL
Change
Icon change arrow
26%
81.63 GL

Total Dam Capacity

South West
80.7%
292.07 GL
Last year
48.4%
175.27 GL
Change
Icon change arrow
66.6%
116.8 GL

Total Dam Capacity

Great Southern
86.8%
2.75 GL
Last year
83.5%
2.65 GL
Change
Icon change arrow
4.2%
0.11 GL

Total Dam Capacity

Mid West
75%
0.02 GL
Last year
75.8%
0.02 GL
Change
Icon change arrow
0%
0 GL

Total Dam Capacity

North West
62.8%
6795.75 GL
Last year
27.7%
2996.73 GL
Change
Icon change arrow
126.8%
3799.02 GL

Dam storage for the last 14 days - metro supply

Dam storage for the last 14 days - metro supply
Year Today 27/11 26/11 25/11 24/11 23/11 22/11 21/11 20/11 19/11 18/11 17/11 16/11 15/11 14/11 13/11 12/11 11/11 10/11 09/11 08/11 07/11 06/11 05/11 04/11 03/11 02/11 01/11 31/10 30/10
2021 N/A N/A 395.6 396.1 396.5 396.8 397.0 397.4 397.7 398.2 398.3 398.7 398.9 399.2 399.6 399.8 400.3 400.5 400.8 401.1 401.4 401.3 401.5 401.4 401.6 401.6 401.7 401.5 401.0 400.9
2020 313.4 313.8 314.0 314.4 314.6 315.0 315.2 315.4 315.6 315.5 315.5 315.6 315.8 315.7 315.4 315.5 315.4 315.3 315.4 313.8 314.1 314.4 314.8 315.1 315.4 315.5 315.6 315.4 315.6 316.0
Comparison N/A N/A +81.6 +81.7 +81.9 +81.8 +81.9 +81.9 +82.2 +82.6 +82.8 +83.2 +83.1 +83.5 +84.2 +84.3 +85.0 +85.2 +85.4 +87.3 +87.3 +86.9 +86.7 +86.4 +86.2 +86.1 +86.1 +86.1 +85.4 +84.9
N/A = Data not available. Storage measured in GL.

Monthly dam volume comparison - metro supply

Select each point to see average monthly dam volume.

Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
2021 293.55 282.85 274.70 267.34 267.16 272.42 295.87 363.28 384.10 395.40 399.41 N/A
2020 294.94 283.32 274.08 267.85 267.04 272.40 283.15 296.38 313.89 318.91 314.88 308.46
2019 333.65 317.65 303.57 291.21 283.69 281.77 291.51 302.77 325.42 326.26 318.98 306.35
2018 270.72 263.17 253.37 249.70 248.40 256.88 278.49 344.19 370.90 371.77 363.19 349.35
2017 197.74 194.59 189.45 186.42 185.27 188.32 197.48 238.72 270.02 285.20 282.51 277.58
2016 163.09 155.03 147.98 146.33 149.90 156.92 163.41 178.38 197.34 209.81 209.94 205.44
2015 219.15 203.51 190.36 183.38 179.93 178.31 175.30 177.08 182.60 182.22 179.52 172.37
2014 212.05 197.95 182.03 170.36 168.22 174.21 188.13 206.14 230.42 248.48 244.79 235.79
N/A = Data not available. Storage measured in GL.

How climate change is impacting our water sources

Water sources for our largest scheme, the Integrated Water Supply Scheme (IWSS) which supplies Perth, the Goldfields and Agricultural Region and some parts of the South West have changed dramatically. Water for the IWSS is now comprised of a combination of sources, including desalinated seawater, groundwater, groundwater replenishment and streamflow into dams.

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. 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.

How Perth's water sources have changed

In 2020-21 the breakdown of Perth's water sources (IWSS) consisted of:

Desalination icon
%
Desalination
Groundwater icon
%
Groundwater
Dams icon
%
Dams
Groundwater replenishment icon
%
Groundwater replenishment