Capacity Optimization of Rainwater Harvesting Systems Based on a Cost–Benefit Analysis: A Financial Support Program Review and Parametric Sensitivity Analysis

Abstract

Water risk has been continuously rising due to climate change and ownership disputes of water resources. Dam construction to secure water resources may lead to environmental problems and upstream immersion. On the other hand, rainwater harvesting systems can effectively supply water at a low cost, although economic efficiency of these systems is still debatable. This study evaluates financial support programs to promote installation of rainwater harvesting systems, increasing economic feasibility. Based on a cost–benefit analysis, capacity optimization methods are further suggested. A sensitivity analysis is performed to determine the relative importance among uncertain parameters such as inflation and discount rates. In doing so, priority factors to consider in the design of rainwater harvesting systems are ultimately identified. A net present value, although it is sensitive to the inflation rate, is shown to be more appropriate to estimate the economic efficiency of rainwater harvesting system, compared to the typical cost–benefit ratio. Because the high future value overestimates the economic feasibility of rainwater harvesting systems, proper inflation rates should be applied. All in all, a funding program to promote rainwater harvesting systems significantly increases the benefits. Thus, national financial support policies are recommended to ensure economic feasibility of rainwater harvesting systems.

Financial Aspects of Sustainable Rainwater Management in Small-Scale Urban Housing Communities

“…The same findings were reported for residential rainwater harvesting systems in Austin, Texas, USA, where studied RWH systems would be not profitable without financial support [80]. A recent paper by Jin et al [81] underlines that national and financial policies promoting rainwater harvesting systems should be available to ensure the economic profitability of these systems and to increase the acceptance of the potential investors and their users' willingness-to-pay. The required community acceptance for rainwater harvesting designs, highly related to the economic issues of such systems, was also underlined as a social aspect of sustainable rainwater management [82].…”

“…The degree of implementation of LID systems varies significantly between different countries all over the world [68][69][70][71][72][73][74][75][76][77][78][79][80][81][82][83][84]. The use of low-impact solutions very often requires additional investment and/or operating costs compared to conventional designs, which may be one of the factors affecting the limited application of these systems.…”

Pollutant Removal Efficiency in a Rainwater Treatment System in Roztocze National Park (Poland)

“…The current state of the art and future perspectives for rainwater harvesting systems in Europe were presented in the paper by Wartalska et al [10], whereas Dalman et al [11] and Jin et al [12] showed the costs and benefits of this subject. On the other hand, de Sá Silva et al [13] presented a review of the environmental, economic, and social aspects of the use of the rainwater harvesting systems.…”

Robust Planning of Irrigation Considering Water Consumption and Revenue

“…Rainwater harvesting (RWH) systems offer a practical way to mitigate water stress. RWH systems provide direct runoff containment while simultaneously storing water, which can then be used for irrigation [Jin et al 2023]. Rainwater harvesting takes attention by individual builgings from the roof top or gardens for individual use.…”