Financial Feasibility of Basic Rainwater Harvesting Systems in Small Residential Communities in Germany: A Secondary Data and Sensitivity Analysis
DOI:
https://doi.org/10.65687/bjbs.v2i1.6Keywords:
rainwater harvesting, financial feasibility, net present value, water tariffs, decentralized water managementAbstract
The study examines the financial feasibility of basic rainwater harvesting systems (RHS) in small German household communities. The objective is to see if RHS is a financially rational household investment under prevailing tariffs and policies. Structured secondary data analysis combined with financial modelling is used in this study. A baseline German scenario is developed using available data on water tariffs, household consumption, and installation costs. The financial performance is assessed using net present value, internal rate of return (IRR), and discounted payback period. A one-variable-at-a-time sensitivity analysis is presented in terms of the effects of tariffs, subsidies, system cost, and discount rate. The results show RHS is financially feasible conditional on some events. With current German tariffs (EUR 5.80-6.40/m³), the systems generate a small positive net present value over 30 years of operation with a discounted payback period of 14-22 years. Reports reveal that financial performance improves significantly under higher tariff scenarios, the availability of installation subsidies, and a lower discount rate. Higher discount rates and lower tariffs, on the contrary, lower viability. The results suggest that RHS is technically feasible and cost-effective; however, its widespread adoption will depend on policies and market conditions that enhance financial attractiveness. The findings of the study will help the policymakers, housing associates, and households to implement targeted subsidies, favorable tariff regimes, and access to low-cost finance for decentralized water management systems.
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