Financial Sustainability of Selected Rain Water Harvesting Systems for Single-Family House under Conditions of Eastern Poland

Abstract

Recent climate changes limiting the available water resources require careful sustainable water management in the cities, the locations of highest drinking water consumption and sanitary sewage and stormwater generation. Over 50% of water demand in the residential areas of cities cover activities in which non-potable water could be used, e.g., toilets and laundry facilities, cleaning, garden irrigation and washing vehicles. Thus, rain water harvesting (RWH) systems are the sustainable alternative water supply, lowering drinking water consumption, by the usage of non-potable harvested water, and limiting the anthropopressure on natural water reservoirs. However, in many cases the social acceptance of RWH and willingness to pay may be affected by financial sustainability, including the affordability and profitability of the investment. This paper presents a case study concerning the financial sustainability of thirteen designs of RWH systems for a single-family house under the climatic and economic conditions of Eastern Poland, one of the poorest regions of the European Union. The financial sustainability of the tested RWH designs were based on indictors of cost-efficiency: dynamic generation cost, payback period, net present value and benefit–cost ratio. The performed analyses showed the limited profitability of the studied RWH designs and the insufficient governmental financial support which may significantly affect the social sustainability of the designs under the local conditions.