By climate change, natural disaster like flood, desertification, elnino and etc happens more than before. Adaptation for climate change becomes important as well as respond globally. One of main issue for adaptation is the water circulation recently. Each countries has been developing technology facilitating water circulation. South Korea also develops low impact development(LID) using rain-water. The rain-water collecting system needs to establish for circulating the rain-water in the household area. The side gutter collecting system and round collecting system have been applied as rain-water collecting system. This study aims at evaluating carbon emission in the life cycle of construction, operation&maintenance, demolition and disposal comparing them with drain collecting system which was developed by life cycle assessment(LCA) methodology. Drain collecting system emitted 2.82 ton CO₂ eq./set, round collection system emitted 27.65 ton CO₂ eq./set and side gutter collection system emitted 21.54 ton CO₂ eq./set. From the result, drain collecting system concluded to reduce over 87% of CO₂ emission in the life cycle besides of other two collecting system. Thus decision-makers need to consider to apply LCA for reducing CO₂ emission designing rainwater collecting system.