Performance of rainwater harvesting systems in the southeastern United States

Recent severe droughts, concerns over the environmental impact of stormwater runoff and increased water demands have generated interest in rainwater harvesting systems in humid, well developed regions, such as the southeastern United States. In order to evaluate the use of rainwater harvesting systems in this region, a monitoring study was conducted at three rainwater cisterns in North Carolina, a computer model was developed to simulate system performance, and simulations were conducted for 208 l rain barrels and larger cisterns. Results of the monitoring study showed that the rainwater harvesting systems were underutilized, which was suspected to result from poor estimation of water usage and public perception of the harvested rainwater. The computer model simulated system performance by evaluating a water balance using historical rainfall data and anticipated usage. Simulation results showed that a rain barrel was frequently depleted when used to meet household irrigation demands and overflowed during most rainfall events. Simulations also illustrated the improved performance of large systems while providing an indication of diminishing returns for increased cistern capacity.