Exploring Options to Optimise Rainwater Tank Size and Efficiency Including potential Benefits of Communal Sharing

Domestic rainwater harvesting is increasingly being used in households in urban areas to reduce dependence on mains water and also to mitigate the adverse impacts of increased stormwater runoff due to urbanization. Most of the literature on rainwater harvesting looks into the installation and use of rainwater tanks by individual households. 

Some of the critical factors that have to be taken into consideration when installing rainwater tanks include roof size, non-potable household water demand, the estimated rainfall in the area, cost of tank (i.e. installation and maintenance costs) and the required level of reliability. 

Can the size of rainwater tanks be optimized to be more cost-efficient while meeting household demand? This is the focus of this paper. The effect of communal rainwater tank (i.e. multiple households using the same rainwater tank), on cost, tank sizing and the ability to cater to water demand are also examined. The possibility of making the process of communal domestic rainwater harvesting system more robust and sustainable by reducing wastage of stored rainwater and reducing the need for larger rainwater tanks has also been studied.

This paper will discuss the outcomes of three case studies and the factors to consider before practical application of these rainwater tank systems.