Rainwater harvesting for home-garden irrigation: a case study in Italy

In residential buildings, drinking water is often used for tasks that do not necessarily require high quality water, such as home-garden irrigation. Our research focuses on the idea of harvesting rainwater to promote sustainable management of low-quality water resources on a building scale for irrigation purposes. The effectiveness of a collection system depends on the weather conditions, which determine also the water need of the plants, on the size of the cultivated area and on the collection surfaces. In this research, a rainwater harvesting system (RWH) for the irrigation of home-gardens in the city of Celano (L'Aquila - Italy) has been analysed. The obtained results show that to maximize water savings a great investment is necessary, i.e. not refundable in a reasonable period due to the low cost of drinking water. On the contrary, to maximize the economic return, it is required a smaller and cheaper tank, but the maximum water savings efficiency decrease to about 60%. In the latter case the RWH system can be cheaper than an irrigation plant supplied by the aqueduct. In the work graphs are provided for practical design use for realizing a RWH system in areas with meteorological conditions similar to those of the survey area, according both the highest water savings efficiency or the highest economic return.