Table showing target and actual water use, dam levels, streamflow and rainfall
Target Actual
May water use to date 10.6 billion litres
10.8 billion litres
Dam storage levels N/A 42.4%
Monthly streamflow into dams N/A 0 billion litres
May rainfall to date 116.9mm (May average rainfall 1876-2016) 51.6mm
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 750 million litres per day – the same as the forecast.

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)
14/05/2021 742 740
13/05/2021 725 740
12/05/2021 778 740
11/05/2021 787 740
10/05/2021 773 762
Note, water use is calculated up to 8am each day for the previous 24 hour period.

Since 1 July 2020, we have used 262.42 billion litres of water – which is 0.81 billion litres below the forecast target for this period.

Dam levels (total for 15 dams)

The dam storage levels are unchanged this week and are sitting at a combined 42.4 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 2021, the dams have received 0.7 billion litres of streamflow. The post-1975 average for the May to April period (called the streamflow year) is 175.63 billion litres.

Sprinkler roster compliance

Since 1 January 2021, we have taken a total of 2,059 actions (warnings + fines) compared with 2,399 actions for the same period in 2020.

Annual rainfall

Perth has received 171.6mm of rainfall since 1 January 2021. The average (1994-2019) rainfall for the same period to the end of May is 173.5mm.

General water news

Did you know that our gardens guzzle more than 40 per cent of water used in the home? But when Mother Nature delivers a good drenching for the garden, as happened across the state last week, it’s a timely reminder to switch off the retic, as your lawn and plants don’t need it.


In fact, if everyone across Perth-Peel switched off their sprinklers for the rest of this month – ahead of the Winter Sprinkler Switch-off – up to three billion litres of water could be saved. That’s enough to fill Optus Stadium three times – imagine that!


We all need to do our bit to save water. The stark reality is that climate change is causing drastically lower rainfall throughout the year and depleting our groundwater sources.


Groundwater, which comes from rain that naturally seeps into the ground, now makes up 70 per cent of all water used in the region.


If you’re using a garden bore, you’re sharing this precious groundwater.


Read more here about how you can be groundwater wise, helping Perth become a leading waterwise city.