Bonacci Water
Date: November, 2008

Project: Monthly Rainwater Report

Subject: Potential water savings of 9,330 million litres from rainwater tanks in Greater Melbourne during November

It is claimed that domestic rainwater tanks will not make a significant contribution to the security of water supplies in Melbourne.

To test this assumption, the monthly rainwater report was established in November 2008 to report on the potential water savings from domestic rainwater tanks, impact on the carbon footprint of supplying water to Melbourne and on water levels in Melbourne’s dams.

Commencing in November 2008, this report will analyse the impact of the missed opportunity in not supporting rainwater tanks as part of Melbourne’s water future.

In order to assess the effectiveness of domestic rainwater harvesting throughout Melbourne it was assumed that 3 kL rainwater tanks are connected to all detached and semi detached housing throughout Greater Melbourne.

Rainfall for November was sourced from the Australian Bureau of Meteorology from 36 locations across Greater Melbourne. Rainwater is collected from 100 m2 roof areas at each dwelling, stored in tanks and used to supply toilet, laundry and outdoor uses.

Total rainwater yields from domestic rainwater tanks for November would be 9,330 million litres.

The current total storage in Melbourne’s dams is 603,287 million litres which is 34% of total capacity of the dams.

The potential water savings from rainwater tanks in November would increase the total storage levels in Melbourne’s dams to 612,620 million litres or 34.6% of total capacity.

The impact of using domestic rainwater tanks on the carbon footprint of Melbourne’s future water supply that includes desalination and transport of water via long pipelines is also assessed.

During November, domestic rainwater tanks would have reduced the carbon footprint of Melbourne’s future water supply strategy by 26,690 tonnes of greenhouse gas emissions.

For further information contact Dr. Peter Coombes on 0419 439 124 or pcoombes@bonacciwater.com. Also see www.bonacciwater.com for more information.

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