[[File:Routing.png|thumb|Conceptual diagram of the excess routing alternatives: On the left, excess flow leaves the cell via an overflow; on the right, excess flow is diverted so that only the design volume enters the cell.]]
==Routing==
*Infiltration facilities can be designed to be inline or offline from the drainage system.
*Inline facilities accept all of the flow from a drainage area and convey larger event flows through an overflow outlet. The overflow must be sized to safely convey larger storm events out of the facility.
:The invert of the overflow should be placed at the maximum water surface elevation of the bioretention area, (typically 150 - 250 mm above the surface).
*Offline facilities use flow splitters or bypass channels that only allow the required water quality storage volume to enter the facility.
:Higher flows are diverted and do not enter the infiltration practice. A pipe can by used for this, but a weir or [[curb cuts|curb cut]] minimizes clogging and reduces the maintenance frequency.