Stressed water resources will lead to water price escalation and water rationing. Alternate water sources such as rainwater are attractive options to handle increasing water demands and drought conditions. Rainfall in Houston, Texas, a humid, sub-tropical region, ranges from three to six inches per month affording ample opportunity to catch and store water. Rainwater system performance and life cycle impacts are critical elements when reviewing the sustainability of a dwelling. However, the utility of rainwater collection systems is a balance of system design, rainfall inputs, water demand, and associated economic costs. The purpose of this research was to investigate the performance and economics of the rainwater collection system and underground cistern in an urban residential setting, focusing on rainfall, rainwater collection and life cycle costs. Field measurements and weather data were used in conjunction with analysis tools to analyze the performance. Daily monthly monitored water demand averages were within 8% of regional averages of 0.347 m~3/day per person or 1.39 m~3/day for a four-person household. Finally, a spreadsheet-based software tool was used to estimate hydraulic performance and economics over a 50-year life cycle. In this research, increasing the size of the rainwater cistern from 10 m~3 to 22.6 m~3 of usable capacity increased payback in net-present value terms from 21 to 43 years.
展开▼
