Green infrastructure can prevent rainfall from entering the water treatment system by allowing it to soak into the soil or to evaporate back into the air. GI-Val tool 2.1 can be used to model the volume and percentage of rainfall that is affected in these ways, and to put a monetary value on part of the benefit: the energy and carbon emission savings. In the case of Valladolid, storm water, domestic sewage and industrial wastewater are collected through a combined sewers system which transports all the wastewater to a sewage treatment plant. The wastewater treatment plant (WWTP) of Valladolid has a treatment capacity for 570,000 population equivalent (future extension up to 750,000 pe) and a maximum flow rate 3 m3/s. The foreseen reduction in the surface runoff by the implementation of the different NBS in Valladolid city will reduce the total volume of wastewater collected though the sewers system and, therefore, the volume of water to be treated at the WWTP. Thus, will suppose an important economic savings.