A windows-based computing tool for rainwater tank analysis and design in multistorey developments

![CDATA[During the current years of water shortage in Australia, the rainwater tank has become an icon of water saving and conservation. For a property owner, one of the considerations in installation of a rainwater tank is how much money a rainwater tank can save over the life time of the tank considering all the costs involved such as the capital cost, operational cost and government subsidy. However, other factors play important role in making decision such as ability of tanks to keep gardens alive during water restrictions and stormwater management benefits. To plan and design a rainwater tank for a given development, many questions need to be answered such as what would be the optimum tank size, how much water and money can be saved and how does a rainwater tank perform during drought years. This paper presents an analytical computer-based tool that can be used to analyse and design rainwater tanks in multistorey buildings. This computer based tool requires various input values such as plot size, roof area, lawn area, daily rainfall data, water demand data, capital cost of the rainwater tank, maintenance cost, interest/discount rates and water price. The output of the tool includes tank size versus water savings graph, benefit-cost ratio and reliability of the rainwater tank in supplying water. An example is included in the paper to demonstrate the application of the program. The program helps to examine various scenarios in relation to the planning and design of a rainwater tank for a multistorey development project. The tool is freely available at this stage by contacting the authors.]]