Perth metro weekly water update

 

	Target	Actual
August water use to date	13 billion litres	13 billion litres
Dam storage levels	N/A	48 per cent
Weekly streamflow into dams	N/A	17 billion litres
August rainfall to date	122.1 mm (August average rainfall 1994-2017)	76.89 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 last week was 591 million litres per day, which was above the forecast of 571 million litres.

 

Daily water use for the last five days
Date	Actual water use (million litres)	Forecast (million litres)
23/08/2019	628	573
22/08/2019	607	573
21/08/2019	594	573
20/08/2019	592	573
19/08/2019	621	567
Note: water use is calculated up to 8am each day for the previous 24 hour period

 

Since 1 July 2019, we have used 30.8 billion litres of water – which is just over the forecast for this period.

 

Dam level (total for 15 dams)

The dam storage levels have remained stable this week and are sitting at a combined 48.4 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 2019 the dams have received 17.3 billion litres of streamflow.  The post-1975 average for the May to April period (called the streamflow year) is 187.2 billion litres.

 

Sprinkler roster compliance

 

The Winter Sprinkler Switch-off is now in place. This means you need to ensure your sprinklers are kept switched off until the end of winter.

 

Our team of inspectors issued 116 warnings and 13 fines this week.  Since 1 January 2019, we have taken a total of 5877 actions (warnings + fines) compared with 5974 actions for the same period in 2018.

 

Annual rainfall

 

Perth has received 473.09 mm of rainfall since 1 January 2019. The cumulative average (1994-2017) rainfall for the January to August period is 572.2 mm.

 

General water news

 

Want to know more about where Perth’s drinking water comes from? In a snapshot, Perth’s largest scheme, the Integrated Water Supply Scheme, consists of:

• 48 per cent desalination

• 40 per cent groundwater

• 10 per cent dams

• 2 per cent groundwater replenishment

 

Desalination or desal involves removing salt from seawater to produce fresh water. It is a reliable water source because it doesn’t depend on rainfall. As we get less rain as a result of climate change, we’ll need to rely on desal more.

Groundwater comes from rain trickling down through soils into the ground. Our groundwater supplies are stored in natural reservoirs called aquifers, which get topped up by rainfall. But, as we're getting less rain, our groundwater supply is declining.

 

Rainfall that’s run off the land into streams eventually ends up in our dams. In the past, Perth relied heavily on our dams as a water source. But now with climate change, we’re getting less rain and dam water is becoming a smaller portion of our water supply.

Instead, our dams have a bigger role to play in water storage. We’re transferring water produced by desalination and deep groundwater into our dams to ensure year-round water supply.

Groundwater replenishment is one of the solutions that will help us become more climate resilient and secure our water supply for generations to come. It involves treating wastewater to the highest drinking water standards, then recharging it into our groundwater supplies. When it’s extracted years later, it’s treated again before arriving to your tap.

To find out more, visit https://www.watercorporation.com.au/water-supply/perths-water-supply