Family Dwelling House Localization in Poland as a Factor Influencing the Economic Effect of Rainwater Harvesting System with Underground Tank

Abstract

Considering water resources, Poland ranks among the last in Europe. By using rainwater for sanitary purposes, drinking water is saved. This article presents the results of the economic analysis of rainwater utilization systems, based on a novel view that takes into account factors related to the location of the family detached house in the country, such as average annual rainfall and water and electricity prices. Two cases of rainwater management systems (domestic-garden and garden) were analyzed in six locations, while considering the diversity of precipitation in Poland in two variants, depending on the material of the tank, with two options of traditional electrical installation or photovoltaic panels. The evaluation of the profitability of the investment was carried out on the basis of indicators: NPV, LCC, and SPBT. The results of the analyses of all variants give the conclusion that, to achieve the greatest financial benefits, it is crucial that the building’s rainwater demand is fully met by rainfall, the unit price of water is significantly higher than the unit price of electricity, operating costs are as low as possible through the use of renewable energy sources, and subsidies are a significant percentage of the investment.