Metropolitan region weekly water update - data as at 19 October 2017

Note: 1 billion litres = 1 Subiaco Oval filled to the goalposts

Broken or damaged water mains and water loss

A water main break on Kingsley/Forrest Hill Drive in Kingsley and another on South West Highway in Mt Richon have recently attracted media interest.

When these types of incidents are reported to us we must send out a crew within two hours to assess the situation, and their key priority is to stop the flow of water.   We do this for three main reasons…

1. To reduce the likelihood of any property flooding

2. To minimise the loss of water

3. To avoid traffic disruption if there is water on a main highway

When these events occur we’re always asked how much water was lost.  It’s really difficult for us to provide an accurate estimate because of how our scheme works.  But rest assured we take all water loss seriously and our prompt response means we aim to keep it to a minimum.

Water Corporation manages more than 14,000 kilometres of water mains across Perth.  Our performance is ranked each year against other water Australian water utilities of a similar size and reported in the National Performance Report. 

Breaks per 100kms of water main – 2015-16 (latest comparison available)

In 2015-16, Perth recorded the lowest water main breaks in six years, with 12 leaks and breaks per 100kms of water main. This was a 20 per cent decrease from the previous year.

We continue to minimise leaks and breaks, with $50.1 million spent in 2017-18 to renew water mains across Perth.  Other actions include our pressure management program, use of permanent and mobile acoustic sensors to listen for the early signs of leaks in the CBD, and our new leak detection dog Kep, who will be out n about sniffing for leaks as soon as she has finished her training.

But despite all of these programs leaks and breaks are an unavoidable factor in all large water supply schemes, and are influenced by the type of pipe, the location of the water main, its age, soil conditions, any nearby construction work or tree root intrusion.

Water use

Our average daily water use last week was 711 million litres, which was below the forecast of 741 million litres per day.  Our financial year to date water use is 66.5 billion litres – good news as it’s less than the 66.97 billion litres we forecast. 

Dam levels

Over the last seven days Perth’s dam storage levels increased from 45.2% to 45.4% (0.2 percentage points).  It’s important to remember Perth’s dams also store ground and desalinated water that is transferred from our treatment plants.

Sprinkler roster compliance

The two-day-per week sprinkler roster now applies, and this week our inspectors issued 48 warnings and 67 fines in the metro region.  This is compared to 28 warnings and 43 fines the previous week.   Year to date we have taken a total of 7,695 actions (warnings + fines) compared to 8,570 actions for the same period in 2016.   

Rainfall

The average monthly rainfall for October is 51.8mm but for the last three years we have received less than this amount.  So far this month we have received 33.6mm of rainfall.  Since 1 January 2017, we have received 800.2mm of rainfall compared to the cumulative average of 811.2mm (January to October).