A study of rainwater tank adoption in Australian households: Selecting the right size for better water-saving performance

Although rainwater tanks have been used in households to save water consumption, their performance is yet to be fully validated. This study analysed the rainwater tank adoption and water-saving performance of 239,269 households in NSW in Australia, via K-means, ANOVA, random forest, and linear regression methods. Four types of rainwater tanks were classified according to their volume and roof collection area: larger rainwater tanks (average of 95 kL), medium rainwater tanks (average of 20 kL), small rainwater tanks with larger roof collection areas (average of 4 kL and average roof collection area of 230 m2), and small rainwater tanks with smaller roof collection areas (average of 3 kL and average roof collection area of 100 m2). The ideal tank volume ranged for small, medium, and large houses was 48 to 79, 61 to 114, and 56 to 139 kL, respectively. In general, this study defined the water-saving effectiveness of different types of rainwater tanks for different water use purposes in different types of houses and proposed optimized strategies for the water use categories as well as tank volumes. Admittedly, the proposed strategies and tank volumes which are based on the big data analysis need to be carefully interpreted considering other factors such as cost and maintenance to provide best guidance to dwellers and the government on adopting and promoting rainwater tanks.