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Want to learn more about how much rainfall we receive and our dam levels? You can view and compare daily, monthly and historical data on the following:

Please note the figures we report are subject to some level of fluctuation throughout the year due to continuous improvement of data collection, validation and quality control.

How often is the data updated?

Metro dam volumes, rainfall and water use data is updated every working day, streamflow data is updated weekly. Read below to find out more about how we record regional dam levels.

Rainfall data updates

We obtain our rainfall figures for the Perth metro area directly from the Bureau of Meteorology’s (BoM) Perth weather station. We update the data daily around 9am or as soon as it becomes available.

Sometimes BoM may adjust the figures later in the day or update data from previous days, which is not always captured in our data. You can view the most up to date rainfall figures on the BoM website.

The below information explains some of the data we collect and record in more detail.

Sometimes we may experience technical difficulties with collecting the data, or we may not have usable readings come through from our teams in the field.

For example, if a dam does not have a reading recorded for a specific date, we will not have data to compare it to the same date last year.

We aim high when it comes to the accuracy of our data but sometimes errors can happen so occasionally we will update historical data.

Our dam level data comes from each of our dams. Our larger dams all have a device that daily measures the volume in each dam. Our smaller dams have a measurement graph painted on the wall of the dam from which our teams take a physical reading each week.

We report metro dam levels to one decimal place now due to the uncertainty in total dam volumes being greater than 0.4-0.5 gigalitres.

Please note that historical total dam volume data changed when we added Stirling and Samson Brook dams.

We need steady regular rain to soak our catchments and get water flowing into our dams. Declining rainfall in Perth means that our dams receive much less streamflow than they used to. Streamflow is the amount of water entering our dams from our catchments and is measured by changing water storage levels.

The water in our dams is also no longer just made up of inflows from rain. Groundwater and desalinated water are also stored in our dams during periods of low demand, making it available in our warmer months, when it's most needed.

A number of regional dams levels are recorded manually by our teams every 2-3 days. Please note that sometimes circumstances prevent levels from being read, so there may be periods when data is unavailable.

Aside from the daily rainfall figures we display, you can also view monthly rainfall totals for Perth, including a graph showing a monthly rainfall comparison.

You can view the monthly rainfall, year to date and seasonal rainfall for the past 4 years in a chart or table view.

Rainfall data has been supplied by the Bureau of Meteorology since 1994.

We started recording rainfall data at all our dams in 1876,  giving us our own historical records for this period.