Abstract: A flushing system and method are provided for substantially reducing sewer solid accumulation in urban drainage systems such that their performance is optimized, their structural integrity is substantially maintained, and pollution of receiving waters is substantially minimized. The flushing system includes at least one flush reservoir that fluidly communicates with the urban drainage system and discharges wet weather flow to flush accumulated sewer solids therefrom. An air release valve on the at least one flush reservoir closes when it is substantially full to create a vacuum that is broken by drawing air through an air intake conduit in the at least one flush reservoir when the urban drainage system is drained to a predetermined level.