Table showing target and actual water use, dam levels, streamflow and rainfall
Target Actual
July water use to date

4.84 billion litres

5.11 billion litres
Dam storage levels N/A 44.5%
Monthly streamflow into dams N/A 1.7 billion litres
July rainfall to date 167.70 mm (July average rainfall 1876-2016) 89.00 mm
Note: 1 billion litres = approximately 400 Olympic swimming pools. Please note the figures in this table are rounded (except for rainfall) to the nearest whole number.

Water use

Average water use over the past week was 638 million litres per day – above the demand forecast of 604 million litres per day.

Daily water use for the last 5 days

Table showing daily water use for the last 5 days
Date Actual water use (million litres) Forecast water use (million litres)
09/07/2021 640 601
08/07/2021 609 601
07/07/2021 611 601
06/07/2021 637 601
05/07/2021 647 607
Note, water use is calculated up to 8am each day for the previous 24 hour period.

Since 1 July 2021, we have used 5.11 billion litres of water – which is 0.27 billion litres above the forecast target for this period.

Dam levels (total for 15 dams)

The dam storage levels are slightly up on last week and are sitting at a combined 44.5 per cent* of full capacity.

*Please note some dams are filled from different sources - dam levels include the transfer of groundwater and desalinated seawater from treatment plants as well as streamflow (that comes from rainfall). As we use many different sources of water, dams are no longer an accurate indicator of the health of Perth's overall water supply situation.

Streamflow (total for 15 dams)

From 1 May 2021, the dams have received 4.7 billion litres of streamflow. The post-1975 average for the May to April period (called the streamflow year) is 175.59 billion litres.

Sprinkler roster compliance

Since 1 January 2021, we have taken a total of 3,648 actions (warnings + fines) compared with 3,450 actions for the same period in 2020.

Annual rainfall

Perth has received 418.2 mm of rainfall since 1 January 2021. The average (1876-2016) rainfall for the same period to the end of July is 543.6mm.

General water news


You may be thinking that with the deluge of rain Perth has received this week, our dams would be getting pretty full, right? Wrong.  While the rain has been very welcome this week, our monthly rainfall totals during winter are still nowhere near what they were 50 years ago.


In fact, the rainfall total for June 2021 in Perth was 45 per cent below the long term (1911-2021) average (169.2mm), with only 93.6mm recorded 12 days1 in June - down from 115.4mm last year and 212mm in 2019.


Climate change is impacting all parts of the state, and while Water Corporation is working hard to identify new water sources such as desalination and groundwater replenishment, securing our water supply requires a combined effort.


Perth residents have done a great job being waterwise in the face of climate change, but there is still more than can be done, and these statistics are another important reminder of that.


This week our water use in Perth was higher than forecast. Being waterwise doesn’t have to require a huge adjustment to your daily life. It could be as simple as cutting your shower by 30 seconds or making sure the tap is turned off while brushing your teeth. If every resident of Perth makes one small waterwise change to their daily life, who knows how much water we could save to secure our water future? 


To find out more about the effects of climate change on our water supply, visit


[1] Source: Bureau of Meteorology - Perth, Western Australia, June 2021 Daily Weather Observations(2 July 2021)