Rainwater pH is in the range of 4.1～4.7 at the first rainfall and it increase a little bit along with amount of rainwater. Color meets the drinking water standards except the first rainfall 3mm but turbidity is above the standard until cumulative rainfall 18mm. Color and turbidity are needed to take into account in rainwater utilization plan.Zn concentration is higher in the industrial area than in other sampling sites. Other heavy metals are detected at trace level or non-detected in almost all the samples. Similarly the pesticides and VOCs are not detected. Ammonia nitrogen concentration is quite high above the standard 0.5mg/L till cumulative rainfall of 6mm. It decreased below 0.5mg/L after cumulative rainfall 12mm for all sampling sites. Organics as KMnO_4 consumption exceeds the standard at the first rainfall of 3mm.From the investigation, it is found that the first rainfall of 3mm is relatively contaminated compared to the drinking water standard however the water quality of subsequent rainfall could meet the standard in all sampling sites. Consequently the rainwater in urban area could be an effective alternative water source if an appropriate collecting technology is applied to the rainwater harvesting.
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