Author(s)

J. Kim, A. Latos

Abstract

Rainwater harvesting is a strategy for reducing a building’s reliance on municipal water. New residential buildings as well as large commercial buildings are increasingly equipped with rainwater collection systems. It is uncertain, however, how significant a role rainwater harvesting plays in achieving a building’s water self-sufficiency. How effective is rainwater harvesting in various climatic zones? Is water self-sufficiency an achievable goal? This paper examines the water self-sufficiency of residential buildings that utilize rainwater harvesting. The test building is a two story single-family house with a population of four residents. The water consumption and rainwater harvesting potential of this standard house were analysed in a range of climatic zones across the US. The continental US is a microcosm of the world’s climates spanning from the arid desert to the humid savanna, from the sub-tropical south to the frigid north. Based on the data published by the United States Geological Surveys (USGS), water consumption of the standard house in 13 test cities was analyzed. Next, the volume of rainwater harvested from the roof of this standard home was estimated. The National Oceanic and Atmospheric Administration (NOAA) 30-year average precipitation data were used in estimating the volume of harvested rainwater. From this study, it was found that rooftop rainwater harvesting can provide at most 25% water self-sufficiency only in subtropical climates. In arid climates, the self-sufficiency was approximately 5% or less, even in rainy months. Drastically conserving water through change in occupant consumption patterns, supplemented with rainwater harvesting, is essential in achieving a building’s water self-sufficiency.

Keywords

sustainability, climate, rainwater harvesting, water self-sufficiency, catchment systems