Lifecycle Analysis of a Single-Family Residential Rainwater Harvesting System in a Subtropical, Metropolitan Environment
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2017 American Society of Civil Engineers. Pressures on water resource availability are a global concern and escalations in water prices and mandatory water rationing make alternate water sources, such as rainwater, more attractive as options to handle increasing water demands and drought conditions. Water system efficiency and lifecycle impacts are factors in building sustainability, and this study investigated the performance and economics of a rainwater collection system and underground cistern in a single-family residential setting, focusing on rainfall, rainwater collection, and lifecycle costs. This study reports on an expanded investigation of the hydraulic and economic performance of residential rainwater harvesting (RWH) systems, including model details, model sensitivity analysis, and a Monte Carlo simulation. Daily water demand averages of 1.39 m3/day were used in the simulation with a 30% variation. Hydraulic inputs, outputs, and economics were evaluated over a 50-year lifecycle. Sensitivity and stochastic analyses were performed with below average, average, and above average estimates of input parameters to assess contributions, and to assess a probabilistic interpretation of the lifecycle results. Using 30-year rainfall normals and Monte Carlo stochastic methods, there was a 45-48% probability of 73% of the annual demand being harvested.