Water Journal : Water Journal April 2011
refereed paper stormwater use water APRIL 2011 129 2010 annual reports of the relevant water agencies or directly from their staff. It should also be recognised that Melbourne and Brisbane have been subject to water restrictions during the 2010 year. Even if the percentage of annual usage is 50% or 60%, as in Perth, Adelaide or Canberra, this is still a significant reduction in reliance on the existing stressed water sources -- worthy of consideration. Conclusion This paper outlines an innovative new approach to managing the increased water demand of growing urban communities by utilising water harvested from the roofs of these growing communities. It has been demonstrated to be the least-cost option in Warrnambool compared to individual rainwater tanks or developing a new groundwater resource. Adoption of this principle is able to reduce the impact of urban growth on the environment by utilising a resource that would otherwise go to waste, avoid transporting water long distances and lower peak flows to rivers and streams. Initial water sampling indicates the water is better than the existing raw water used in Warrnambool for many of the parameters, but has higher microbiological counts, which is likely to be a result of the water being stored in a sump before pumping to the larger storage. The resulting raw water quality is still well within the historic variability of microbiological counts and accordingly is of no concern to the downstream treatment barrier. Higher levels of zinc were measured but these were still two orders of magnitude below the Australian Drinking Water Guidelines. The measured volume of water harvested during the first six months of operation has exceeded the demand from the 11 houses already connected. This occurred during the higher rainfall and lower temperature months of July to September as expected, but has continued through to December due to the wetter than normal year. The paper explains the operation of the Toolkit, data sets used and the input data required to allow it to calculate the volume harvested in an average year and the cost/ML of that water. The Toolkit has the flexibility to allow various system arrangements to be explored and optimisation of these through repeated runs of the package. The Toolkit is easy to use and allows water resource planners to quickly explore the opportunities for regional roof water harvesting in their region. Footnote: This is an updated version of the paper presented at the Sustainable Infrastructure and Asset Management Conference, November 2010. The Author Peter Wilson (email peter.wilson@ wannonwater.com.au) is Branch Manager Asset Planning with Wannon Region Water Corporation, Warrnambool, Victoria. Acknowledgement Funding has been provided through the Australian Federal Government's Water for the Future Program and the Victorian State Government Stormwater and Urban Recycling Fund, allowing the demonstration site to be established and the regional harvesting principle to be explored in other areas of Australia. Resources • Water Services Association of Australia, National Water Commission and the NWI Parties (2009). National Performance Report 2007-2008. Urban Water Utilities. Canberra, ACT, Australia: National Water Commission. • Hallmann M, Grant T, Alsop N, January 2003: Yarra Valley Water Life Cycle Assessment and Life Cycle Costing of Water Tanks as a Supplement to Mains Water Supply. Centre for Design at RMIT University, Melbourne, Vic, Australia. • www.esc.vic.gov.au/NR/ rdonlyres/8B4CD53D-F6C5-43EE-9C61- 7513DE9CBB64/0/RPT200910urbanwater- performancereports20101214.pdf • www.sydneywater.com.au/Publications/ Reports/AnnualReport/2010/performance/ water_efficiency.html • www.sawater.com.au/NR/ rdonlyres/8CD917F5-4B79-4670-A76F- 6E614EC81CD0/0/AnnualReport0910.pdf • www.watercorporation.com.au/_fles/ PublicationsRegister/6/Water_Corpora- tion_Annual_Report_2010.pdf Peter Wilson looking over the Brierly Raw Water Basin, receiving storage for harvested roof water. The tiled roofs seen in the background are connected to the system.
Water Journal March 2011
Water Journal May 2011