Metro weekly water update – 3 August 2018





August water use to date

551 million litres

535 million litres

Dam storage levels



Streamflow into dams
(cumulative May 2018 – April 2019)

25 billion litres

33.8 billion litres

August rainfall to date

122.1 mm

(August mean rainfall 1994-2017)

32.8 mm

Note: 1 billion litres = approx. 400 Olympic swimming pools.  Please note these figures are rounded (except for rainfall) to the nearest whole number.


Water use


Average daily water use over the last week was 535 million litres, which was below the forecast of 551 million litres.  Since 1 August 2018 we have used 1.1 billion litres of water, which is spot on target to the forecast.


Dam levels


Over the last seven days, Perth’s dam storage levels have increased (by 8 billion litres) from 283 billion litres to 291 billion litres of usable storage. Perth’s dams store water from three different sources… groundwater and desalinated seawater transferred from treatment plants as well as streamflow (produced by rainfall).




Over the last seven days Perth’s dams (15 dams in total) have received about 8.7 billion litres of streamflow.  Since May, they have received about 33 billion litres of streamflow.


Sprinkler roster compliance


The Winter Sprinkler Switch-off now applies, and our inspectors issued 102 warnings and 11 fines this week.  Since 1 January 2018, we have taken a total of 6113 actions (warnings + fines) compared with 6418 actions for the same period in 2017.


Annual rainfall

Perth has received 522 mm of rainfall since January this year.  According to updated figures released by the Bureau of Meteorology the cumulative mean rainfall (1994-2017) for the Perth metro for the January to December is 732.8 mm.


General water news

It was great to see July’s monthly rainfall in Perth come in at just over the average for the month, and lots of people are saying it feels like it has been a really wet winter so far.

At Water Corporation the important figure for us is streamflow – or the amount of water that soaks our catchments and flows into the dams. At the moment streamflow is 33 billion litres of water, which is encouraging and means the Avon Descent will be a real spectacle this weekend.

But the post-1975 average for streamflow is actually 187 billion litres a year and before 1975 the average was much higher at 420 billion litres a year (a streamflow year being from May to April).

So while it does seem like it has been a wet winter, the impact of climate change in the south west of WA is being seen in the declining streamflow our dams receive over the past 40 years.

This is why it is so important to keep your garden sprinklers off during these wetter and cooler months, so we can all save water for when it is most needed.

For more streamflow data, go to Streamflow into dams