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Perth metro weekly water update – 21 August 2020




August water use to date

12.4 billion litres

12.5 billion litres

Dam storage levels


47.6 per cent

Monthly streamflow into dams


6.27 billion litres

August rainfall to date

132.9 mm

(August average rainfall 1994-2017)

88.8 mm

Note: 1 billion litres = approx. 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 584 million litres per day, which was below the forecast of 588 million litres.


Daily water use for the last five days


Actual water use (million litres)

Forecast (million litres)
















Note: water use is calculated up to 8am each day for the previous 24 hour period


Since 1 July 2020 to date, we have used 29.75 billion litres of water – which is 0.4 billion litres under the forecast target for this period.


Dam level (total for 15 dams)

The dam storage levels have risen slightly this week and are sitting at a combined 47.6 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 2020 the dams have received 17.9 billion litres of streamflow.  The post-1975 average for the May to April period (called the streamflow year) is 178.21 billion litres.


Sprinkler roster compliance


The winter sprinkler switch off now applies. Since 1 January 2020, we have taken a total of 4692 actions (warnings + fines) compared with 6495 actions for the same period in 2019.


Annual rainfall


Perth has received 486.4mm of rainfall since 1 January 2020. The average (1994-2019) rainfall for the same period is 510.6 mm.



General water news


Following two large ‘pipe monsters’ found blocking wastewater systems in Kojonup, residents across the state are being urged to think twice about what they flush down the toilet, or wash down the sink.


Water Corporation removes between 200 to 300 kilograms of material causing wastewater blockages each year, often referred to as ‘pipe monsters’ or ‘fatbergs’ that cause havoc in local wastewater systems.


Kitchen towel, cotton buds, wet wipes, nappies, sanitary products, jocks, socks and plastic bags should not be flushed down the toilet, as this material does not break down like toilet paper. Also do not pour fat, oil or grease straight down the kitchen sink, as once cooled, it solidifies and causes blockages.


Remember, only soap and water down the sink, and toilet paper, pee and poo down the loo.

To learn more and see a photo of a pipe monster click here.