Mendez et al. [18] and Nicholson et al. [24] stated that every artificial
roofing material affect the runoff, however the water studied
from sample green roofs added less chemical compounds and
usually met the US EPA standards. However, it is important to note
that the Mendez et al. [18] research did not consider the possibility
of adding fertilizers and pesticides to protect and enhance plants
growth by ordinary owners, resulting in more chemicals in runoff
water.