Water saving and cost analysis of large-scale implementation of domestic rain water harvesting in minor Mediterranean islands

This paper describes a novel methodology to evaluate the benefits of large-scale installation of domestic Rain Water Harvesting (RWH) systems in multi-story buildings. The methodology was specifically developed for application to small settlements of the minor Mediterranean islands characterized by sharp fluctuations in precipitation and water demands between winter and summer periods. The methodology is based on the combined use of regressive models for water saving evaluation and of geospatial analysis tools for semi-automatic collection of spatial information at the building/household level. An application to the old town of Lipari (Aeolian islands) showed potential for high yearly water savings (between 30% and 50%), with return on investment in less than 15 years for about 50% of the installed RWH systems.