Rainwater Harvesting System as an Alternative Water Source for Domestic and Outdoor Uses

Abstract

Abstract A naturally distilled rainwater (<10 mg/L mineral content) is readily available when captured and stored. Capturing and utilizing rainwater is thousands of years old technique for human survival and is extensively used in arid and semi-arid regions of the world. Even though the annual average rainfall in humid Alabama is 1,397 mm great variability exists on a weekly and monthly basis monthly rainfall ranges from 71 – 155 mm which makes rainwater harvesting ideal for Alabama. In many areas of Alabama, dry spells alternate with heavy rainfall events that cause excessive overland flow and soil erosion. Roof Catchment of Rainwater (RCR) can thus help reduce excessive overland flow and soil erosion problems while providing an alternative source of water for non-potable domestic, agricultural and industrial uses. It can also reduce water bills and reduce strain on groundwater pumping and/or municipal water systems. The objectives of this study were to install RCR systems at a typical single family house and a school in Alabama, and evaluate the feasibility and efficiency of using the RCR systems for water harvesting in Alabama. The RCR systems were equipped with a control system and a CR10X data logger to monitor the system operation and to collect data on precipitation, temperature, overflow, water depth in the storage tank and daily uses of toilet flushing. Daily average water use of the home for toilet flushing was 95 liter and 2100 liter was used at the school during the school days. Rainwater harvesting efficiency was 83.3 and 89 percent and RCR use efficiency was 18 and 98 percent from the home and the school, respectively. A computer program was developed to estimate potential effectiveness of RCR systems. From the analysis result with 10 years rainfall data, a total of 67,000 liters of rainwater could be harvested for domestic uses from a typical single family house in Alabama which supplies 190 liters per day.