Feasibility analysis of a small-scale rainwater harvesting system for drinking water production at Werrington, New South Wales, Australia

Abstract

Rainwater harvesting is a well-known method of collecting and storing rainwater that can subsequently be used for different purposes. Most of the recent studies focused on how to use the harvested rainwater effectively to reduce the use of potable water for non-potable usage and ultimately cut down the water demand from the mains. However, studies on rainwater harvesting system have rarely been undertaken for drinking water production at the household level in rural areas, where a centralised water supply system is unavailable. The present study reports the feasibility of a small-scale rainwater harvesting system intended to produce drinking water for rural/isolated communities. A number of parameters such as roof size, tank size, water demand and daily filtration rate were taken into consideration to examine the performance of the rainwater harvesting system. Local meteorological and costing data were used in the study assuming that the system would provide drinking water to a typical household of four people. It is found that the small-scale rainwater harvesting system can satisfy the drinking water demand throughout the year with 90–97% reliability depending on the roof size. In addition, the capacity of monthly water production from different rainwater harvesting systems is presented that can be adopted to increase the reliability further. A life cycle cost analysis of the system is presented including sensitivity analysis. It is found that the preferred rainwater tank size for a household having 100 m2 roof area in Werrington, New South Wales is 5 kL. The system payback time falls between 1 and 6 years depending on the price of the produced drinking water. The cost of the produced drinking water including disinfection and mineral addition is found to be 1.04 AU₵/L. In addition, the intended rainwater harvesting system could result in a monetary return of AU$ 35,494 over its lifetime of 25 years. This study shows that the production of drinking water by rainwater harvesting for rural communities is possible at an affordable cost, which is aligned to the United Nation’s Sustainable Development Goal 6: Clean Water and Sanitation.