Estimation of Actual Water Savings from a Household Rainwater Harvesting System Using MyWell App

The declining access to the renewable fresh water sources is likely to result in inadequate water supply worldwide. Experts have recently tried to identify reliable, sustainable, and cost-effective fresh water supply sources. Hence, a great number of research on water savings suggest the rainwater harvesting system as one of the reliable alternatives to save fresh water. According to studies, a household rainwater harvesting system can supply 12% to 100% of its non-potable water demand based on household size, roof area, rainfall patterns and other relevant factors. The aim of this study is to estimate water savings from a roof-top based rainwater harvesting system. The daily data are collected using MyWell app. This smartphone app is developed under a groundwater monitoring project which allows public in real time monitoring of rainfall, water level, water quality and others. Primarily, this research focuses on water savings for a specific household located in Pendel Hills, a suburb of Greater Sydney region. The study household has a rainwater tank of 5 kL. All the study data from MyWell app and other secondary sources are collected for a one-year period from June 2020 to June 2021. To calculate the water savings, authors have used two approaches- (a) the theoretical approach using ‘Behavioural-Storage model’ and (b) Real-time water demand and supply estimation. This study only considered non-potable uses of the harvested rainwater. The results show that the selected rainwater tank is about to save approximately 6.39 m3 water each month (40% of demand) in the theoretical approach. While the rainwater tank is saving an average of 2.42 m3 /month water in real-time which is only 19.75% of monthly water demand. The results of this study will help to improve rainwater harvesting system performance and will contribute to achieve water related sustainable development goals.