The soil in green roof systems acts like a sponge and absorbs excess rain water. Research has shown that extensive green roof systems can reduce runoff by up to 90+% annually (varies with climate, soil and pitch of roof). Green roofs reduce the impact of each new building on the municipal storm drainage system and surrounding watershed. They reduce flooding, erosion and artificial heating of water which helps preserve fisheries and other aquatic life. Green roofs reduce the need for on-site storm water management systems and according to Seattle based Magnusson Klemencic Associates, under certain conditions, can offset the cost of a green roof by 30 to 60%. When combined with an effective rain garden (bioswale), green roofs can make it possible to have zero discharge of rainwater from the site, therefore saving money by not having to connect to the storm sewer system. The LiveRoof® System can help you achieve LEED certification in several categories.