Evaluation of the qualities of rainwater collected from the top of vinyl house : A Case Study in Jeju Island

Recently there has been a great deal of interest in promotion of the utilization of rainwater. In this paper, we comparedqualities of the rainwater collected from the top of vinyl houses to those of precipitated rainwater itself in Jeju Island. The pH ofthe collected rainwater was acidic and lower than the precipitated one. As a storm progresses, the pH of the collected watergradually increases. Ranges of EC of the precipitated and collected rainwater were 1-118 and 1-475 μS/cm. Most of Cl andturbidity values of the collected rainwater were less than 20 mg/L and 20 NTU, while those of the precipitated rainwater wereless than 10 mg/L and 5 NTU. Differences in qualities between precipitated and collected rainwater indicate that qualities of thecollected rainwater should be changed by the first flush effects, and imply that long term continuous monitoring for thequalities of collected rainwater is essential to quantify the first flush phenomenon more accurately.