Financial and Social Factors Influencing the Use of Unconventional Water Systems in Single-Family Houses in Eight European Countries

Abstract

A modern model of water management should take into account, first of all, its responsible consumption of both tap water and water from unconventional sources. With this in mind, a study was conducted to determine the financial efficiency of rainwater harvesting systems (RWHSs) and greywater recycling systems (GWRSs) in residential buildings located in eight European countries. At the first stage, volumetric reliability was determined for different tank capacities for actual precipitation data. An economic analysis was carried out for six variants in which rainwater and greywater were used in various combinations for toilet flushing, washing, and garden watering. The implementation of alternative water systems was found to be financially unprofitable in four cities: Warsaw, Bratislava, Budapest, and Stockholm. For these cities, the variant with the lowest life cycle cost (LCC) level was always Variant 0, with conventional installations. The opposite situation was observed in the other four locations (Lisbon, Madrid, Rome, and Prague), where Variant 0 was not found to be financially profitable for any of the calculation cases analyzed. Additionally, a survey was conducted to determine the effect of social aspects, which is often the greatest barrier to the implementation of new or unknown technologies. In most of the countries surveyed, rainwater is more acceptable to society as an alternative water source than greywater. For hygiene reasons, the use of these two systems for washing clothes was of greatest concern.